feat: Complete light mode implementation with semantic theme system

- Add comprehensive light/dark mode CSS variables with semantic naming
- Implement theme-aware scrollbars using CSS variables
- Add light mode backgrounds: --bg-base, --bg-elevated, --bg-surface, etc.
- Add theme-aware borders: --border-base, --border-panel, --border-subtle
- Add semantic text colors: --foreground-secondary, --foreground-subtle
- Convert oklch colors to hex for better compatibility
- Add theme awareness to CodeMirror editors
- Update dark mode colors for consistency (background, sidebar, card, muted, input)
- Add Tailwind color mappings for semantic classes

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

@@ -1939,11 +1939,11 @@ function FileManagerContent({ initialHost, onClose }: FileManagerProps) {
   }
 
   return (
-    <div className="h-full flex flex-col bg-dark-bg">
-      <div className="flex-shrink-0 border-b border-dark-border">
+    <div className="h-full flex flex-col bg-canvas">
+      <div className="flex-shrink-0 border-b border-edge">
         <div className="flex items-center justify-between p-3">
           <div className="flex items-center gap-2">
-            <h2 className="font-semibold text-white">{currentHost.name}</h2>
+            <h2 className="font-semibold text-foreground">{currentHost.name}</h2>
             <span className="text-sm text-muted-foreground">
               {currentHost.ip}:{currentHost.port}
             </span>
@@ -1956,11 +1956,11 @@ function FileManagerContent({ initialHost, onClose }: FileManagerProps) {
                 placeholder={t("fileManager.searchFiles")}
                 value={searchQuery}
                 onChange={(e) => setSearchQuery(e.target.value)}
-                className="pl-8 w-48 h-9 bg-dark-bg-button border-dark-border"
+                className="pl-8 w-48 h-9 bg-button border-edge"
               />
             </div>
 
-            <div className="flex border border-dark-border rounded-md">
+            <div className="flex border border-edge rounded-md">
               <Button
                 variant={viewMode === "grid" ? "default" : "ghost"}
                 size="sm"