Add system tray / minimize to tray (roadmap #8)

- tauri "tray-icon" feature enabled
- Tray icon created on startup using the app's default window icon
- Tray menu: "Open Wrystr" (show + focus) and "Quit" (app.exit)
- Left-click on tray icon: show + focus the main window
- Right-click: context menu (platform default)
- Window close button (X) now hides to tray instead of exiting —
  "Quit" in the tray menu is the exit point
- Works on Windows (system tray), Linux (status bar tray), macOS
  (menu bar); DE-specific tray support varies on Linux

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -5066,7 +5066,7 @@ dependencies = [
 
 [[package]]
 name = "wrystr"
-version = "0.1.1"
+version = "0.1.2"
 dependencies = [
  "keyring",
  "rusqlite",