feat: add compact mode for minimal widget interface (#36)

Add a compact mode that shrinks the window to a small widget showing
just the character sprite, recent messages, and a quick input box.
Perfect for quick questions while working without the full UI.

- Add CompactMode.svelte component with minimal widget interface
- Add compact mode toggle in StatusBar (Ctrl+Shift+M shortcut)
- Save/restore window size when toggling compact mode
- Handle display scaling by converting physical to logical pixels
- Add compact_mode to config (Rust + TypeScript)
- Add required Tauri window permissions for resize operations

src-tauri/capabilities/default.json

@@ -19,6 +19,9 @@
     "core:tray:default",
     "fs:default",
     "fs:allow-read-text-file",
-    "fs:allow-write-text-file"
+    "fs:allow-write-text-file",
+    "core:window:allow-set-size",
+    "core:window:allow-set-always-on-top",
+    "core:window:allow-inner-size"
   ]
 }