feat: add system, uptime, network and processes widgets

Add four new server statistics widgets:
- SystemWidget: displays hostname, OS, and kernel information
- UptimeWidget: shows server total uptime with formatted display
- NetworkWidget: lists network interfaces with IP and status
- ProcessesWidget: displays top processes by CPU usage

Backend changes:
- Extended SSH metrics collection to gather network, uptime, process, and system data
- Added commands to parse /proc/uptime, ip addr, ps aux output

Frontend changes:
- Created 4 new widget components with consistent styling
- Updated widget type definitions and HostManagerEditor
- Unified all widget heights to 280px for consistent layout
- Added translations for all new widgets (EN/ZH)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/types/stats-widgets.ts

@@ -1,9 +1,16 @@
-export type WidgetType = "cpu" | "memory" | "disk";
+export type WidgetType =
+  | "cpu"
+  | "memory"
+  | "disk"
+  | "network"
+  | "uptime"
+  | "processes"
+  | "system";
 
 export interface StatsConfig {
   enabledWidgets: WidgetType[];
 }
 
 export const DEFAULT_STATS_CONFIG: StatsConfig = {
-  enabledWidgets: ["cpu", "memory", "disk"],
+  enabledWidgets: ["cpu", "memory", "disk", "network", "uptime", "system"],
 };