Fix paste-to-app, settings highlight, and titleBarStyle casing

Paste fix:
- Switch from std::process::Command to tokio::process::Command to avoid
  blocking the async runtime (was stalling the paste action)
- Use explicit AppleScript that activates the frontmost app before sending
  Cmd+V keystroke, making paste more reliable
- Increase delay to 300ms for macOS app refocus
- Add tokio "process" feature

Settings highlight fix:
- SettingsPanel now uses local useState for immediate optimistic updates
  when clicking position/history buttons, instead of waiting for the
  parent prop round-trip
- Buttons highlight instantly on click, then sync with backend

Config fix:
- titleBarStyle must be PascalCase "Overlay" in Tauri 2 config (was
  lowercase "overlay" which caused a startup error)

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/Cargo.toml

@@ -26,7 +26,7 @@ base64 = "0.22"
 log = "0.4"
 png = "0.17"
 dirs = "5"
-tokio = { version = "1", features = ["time", "macros"] }
+tokio = { version = "1", features = ["time", "macros", "process"] }
 
 [target.'cfg(target_os = "macos")'.dependencies]
 core-graphics = "0.24"