feat: Enhanced security, UI improvements, and animations (#432)

* fix: Remove empty catch blocks and add error logging

* refactor: Modularize server stats widget collectors

* feat: Add i18n support for terminal customization and login stats

- Add comprehensive terminal customization translations (60+ keys) for appearance, behavior, and advanced settings across all 4 languages
- Add SSH login statistics translations
- Update HostManagerEditor to use i18n for all terminal customization UI elements
- Update LoginStatsWidget to use i18n for all UI text
- Add missing logger imports in backend files for improved debugging

* feat: Add keyboard shortcut enhancements with Kbd component

- Add shadcn kbd component for displaying keyboard shortcuts
- Enhance file manager context menu to display shortcuts with Kbd component
- Add 5 new keyboard shortcuts to file manager:
  - Ctrl+D: Download selected files
  - Ctrl+N: Create new file
  - Ctrl+Shift+N: Create new folder
  - Ctrl+U: Upload files
  - Enter: Open/run selected file
- Add keyboard shortcut hints to command palette footer
- Create helper function to parse and render keyboard shortcuts

* feat: Add i18n support for command palette

- Add commandPalette translation section with 22 keys to all 4 languages
- Update CommandPalette component to use i18n for all UI text
- Translate search placeholder, group headings, menu items, and shortcut hints
- Support multilingual command palette interface

* feat: Add smooth transitions and animations to UI

- Add fade-in/fade-out transition to command palette (200ms)
- Add scale animation to command palette on open/close
- Add smooth popup animation to context menu (150ms)
- Add visual feedback for file selection with ring effect
- Add hover scale effect to file grid items
- Add transition-all to list view items for consistent behavior
- Zero JavaScript overhead, pure CSS transitions
- All animations under 200ms for instant feel

* feat: Add button active state and dashboard card animations

- Add active:scale-95 to all buttons for tactile click feedback
- Add hover border effect to dashboard cards (150ms transition)
- Add pulse animation to dashboard loading states
- Pure CSS transitions with zero JavaScript overhead
- Improves enterprise-level feel of UI

* feat: Add smooth macOS-style page transitions

- Add fullscreen crossfade transition for login/logout (300ms fade-out + 400ms fade-in)
- Add slide-in-from-right animation for all page switches (Dashboard, Terminal, SSH Manager, Admin, Profile)
- Fix TypeScript compilation by adding esModuleInterop to tsconfig.node.json
- Pass handleLogout from DesktopApp to LeftSidebar for consistent transition behavior

All page transitions now use Tailwind animate-in utilities with 300ms duration for smooth, native-feeling UX

* fix: Add key prop to force animation re-trigger on tab switch

Each page container now has key={currentTab} to ensure React unmounts and remounts the element on every tab switch, properly triggering the slide-in animation

* revert: Remove page transition animations

Page switching animations were not noticeable enough and felt unnecessary.
Keep only the login/logout fullscreen crossfade transitions which provide clear visual feedback for authentication state changes

* feat: Add ripple effect to login/logout transitions

Add three-layer expanding ripple animation during fadeOut phase:
- Ripples expand from screen center using primary theme color
- Each layer has staggered delay (0ms, 150ms, 300ms) for wave effect
- Ripples fade out as they expand to create elegant visual feedback
- Uses pure CSS keyframe animation, no external libraries

Total animation: 800ms ripple + 300ms screen fade

* feat: Add smooth TERMIX logo animation to transitions

Changes:
- Extend transition duration from 300ms/400ms to 800ms/600ms for more elegant feel
- Reduce ripple intensity from /20,/15,/10 to /8,/5 for subtlety
- Slow down ripple animation from 0.8s to 2s with cubic-bezier easing
- Add centered TERMIX logo with monospace font and subtitle
- Logo fades in from 80% scale, holds, then fades out at 110% scale
- Total effect: 1.2s logo animation synced with 2s ripple waves

Creates a premium, branded transition experience

* feat: Enhance transition animation with premium details

Timing adjustments:
- Extend fadeOut from 800ms to 1200ms
- Extend fadeIn from 600ms to 800ms
- Slow background fade to 700ms for elegance

Visual enhancements:
- Add 4-layer ripple waves (10%, 7%, 5%, 3% opacity) with staggered delays
- Ripple animation extended to 2.5s with refined opacity curve
- Logo blur effect: starts at 8px, sharpens to 0px, exits at 4px
- Logo glow effect: triple-layer text-shadow using primary theme color
- Increase logo size from text-6xl to text-7xl
- Subtitle delayed fade-in from bottom with smooth slide animation

Creates a cinematic, polished brand experience

* feat: Redesign login page with split-screen cinematic layout

Major redesign of authentication page:

Left Side (40% width):
- Full-height gradient background using primary theme color
- Large TERMIX logo with glow effect
- Subtitle and tagline
- Infinite animated ripple waves (3 layers)
- Hidden on mobile, shows brand identity

Right Side (60% width):
- Centered glassmorphism card with backdrop blur
- Refined tab switcher with pill-style active state
- Enlarged title with gradient text effect
- Added welcome subtitles for better UX
- Card slides in from bottom on load
- All existing functionality preserved

Visual enhancements:
- Tab navigation: segmented control style in muted container
- Active tab: white background with subtle shadow
- Smooth 200ms transitions on all interactions
- Card: rounded-2xl, shadow-xl, semi-transparent border

Creates premium, modern login experience matching transition animations

* feat: Update login page theme colors and add i18n support

- Changed login page gradient from blue to match dark theme colors
- Updated ripple effects to use theme primary color
- Added i18n translation keys for login page (auth.tagline, auth.description, auth.welcomeBack, auth.createAccount, auth.continueExternal)
- Updated all language files (en, zh, de, ru, pt-BR) with new translations
- Fixed TypeScript compilation issues by clearing build cache

* refactor: Use shadcn Tabs component and fix modal styling

- Replace custom tab navigation with shadcn Tabs component
- Restore border-2 border-dark-border for modal consistency
- Remove circular icon from login success message
- Simplify authentication success display

* refactor: Remove ripple effects and gradient from login page

- Remove animated ripple background effects
- Remove gradient background, use solid color (bg-dark-bg-darker)
- Remove text-shadow glow effect from logo
- Simplify brand showcase to clean, minimal design

* feat: Add decorative slash and remove subtitle from login page

- Add decorative slash divider with gradient lines below TERMIX logo
- Remove subtitle text (welcomeBack and createAccount)
- Simplify page title to show only the main heading

* feat: Add diagonal line pattern background to login page

- Replace decorative slash with subtle diagonal line pattern background
- Use repeating-linear-gradient at 45deg angle
- Set very low opacity (0.03) for subtle effect
- Pattern uses theme primary color

* fix: Display diagonal line pattern on login background

- Combine background color and pattern in single style attribute
- Use white semi-transparent lines (rgba 0.03 opacity)
- 45deg angle, 35px spacing, 2px width
- Remove separate overlay div to ensure pattern visibility

* security: Fix user enumeration vulnerability in login

- Unify error messages for invalid username and incorrect password
- Both return 401 status with 'Invalid username or password'
- Prevent attackers from enumerating valid usernames
- Maintain detailed logging for debugging purposes
- Changed from 404 'User not found' to generic auth failure message

* security: Add login rate limiting to prevent brute force attacks

- Implement LoginRateLimiter with IP and username-based tracking
- Block after 5 failed attempts within 15 minutes
- Lock account/IP for 15 minutes after threshold
- Automatic cleanup of expired entries every 5 minutes
- Track remaining attempts in logs for monitoring
- Return 429 status with remaining time on rate limit
- Reset counters on successful login
- Dual protection: both IP-based and username-based limits

src/ui/desktop/apps/file-manager/FileManagerContextMenu.tsx

@@ -19,6 +19,7 @@ import {
   Bookmark,
 } from "lucide-react";
 import { useTranslation } from "react-i18next";
+import { Kbd, KbdGroup } from "@/components/ui/kbd";
 
 interface FileItem {
   name: string;
@@ -101,9 +102,15 @@ export function FileManagerContextMenu({
 }: ContextMenuProps) {
   const { t } = useTranslation();
   const [menuPosition, setMenuPosition] = useState({ x, y });
+  const [isMounted, setIsMounted] = useState(false);
 
   useEffect(() => {
-    if (!isVisible) return;
+    if (!isVisible) {
+      setIsMounted(false);
+      return;
+    }
+
+    setIsMounted(true);
 
     const adjustPosition = () => {
       const menuWidth = 200;
@@ -182,8 +189,6 @@ export function FileManagerContextMenu({
     };
   }, [isVisible, x, y, onClose]);
 
-  if (!isVisible) return null;
-
   const isFileContext = files.length > 0;
   const isSingleFile = files.length === 1;
   const isMultipleFiles = files.length > 1;
@@ -425,13 +430,38 @@ export function FileManagerContextMenu({
     return index > 0 && index < filteredMenuItems.length - 1;
   });
 
+  const renderShortcut = (shortcut: string) => {
+    const keys = shortcut.split("+");
+    if (keys.length === 1) {
+      return <Kbd>{keys[0]}</Kbd>;
+    }
+    return (
+      <KbdGroup>
+        {keys.map((key, index) => (
+          <Kbd key={index}>{key}</Kbd>
+        ))}
+      </KbdGroup>
+    );
+  };
+
+  if (!isVisible && !isMounted) return null;
+
   return (
     <>
-      <div className="fixed inset-0 z-[99990]" />
+      <div
+        className={cn(
+          "fixed inset-0 z-[99990] transition-opacity duration-150",
+          !isMounted && "opacity-0"
+        )}
+      />
 
       <div
         data-context-menu
-        className="fixed bg-dark-bg border border-dark-border rounded-lg shadow-xl min-w-[180px] max-w-[250px] z-[99995] overflow-hidden"
+        className={cn(
+          "fixed bg-dark-bg border border-dark-border rounded-lg shadow-xl min-w-[180px] max-w-[250px] z-[99995] overflow-hidden",
+          "transition-all duration-150 ease-out origin-top-left",
+          isMounted ? "opacity-100 scale-100" : "opacity-0 scale-95"
+        )}
         style={{
           left: menuPosition.x,
           top: menuPosition.y,
@@ -470,9 +500,9 @@ export function FileManagerContextMenu({
                 <span className="flex-1">{item.label}</span>
               </div>
               {item.shortcut && (
-                <span className="text-xs text-muted-foreground ml-2 flex-shrink-0">
-                  {item.shortcut}
-                </span>
+                <div className="ml-2 flex-shrink-0">
+                  {renderShortcut(item.shortcut)}
+                </div>
               )}
             </button>
           );