feat(overlay): forward mpv mouse and wheel bindings through overlay

- Accept WHEEL_UP/DOWN/LEFT/RIGHT (with modifiers) in keybindings, the plugin, and the settings key editor
- Forward mpv's MBTN_* and WHEEL_* bindings from the overlay so double-click fullscreen, wheel volume, and similar inputs work on Hyprland; SubMiner bindings and right-click pause still win
- Notify the overlay via mpv-input-bindings:changed when mpv's key set changes, fixing dead imported keys when the overlay loads before mpv connects
- Sync README requirements/quick start with the installation guide and fix the Arch MeCab install command (AUR mecab-git)

src/main.ts

@@ -5540,6 +5540,8 @@ const { persistSessionBindings, refreshCurrentSessionBindings, refreshMpvSession
     logWarn: (message) => logger.warn(message),
     onBindingsChanged: (bindings) =>
       overlayManager.broadcastToOverlayWindows(IPC_CHANNELS.event.sessionBindingsChanged, bindings),
+    onMpvInputBindingsChanged: () =>
+      overlayManager.broadcastToOverlayWindows(IPC_CHANNELS.event.mpvInputBindingsChanged),
     onWarning: (warning) => {
       if (warning.kind !== 'conflict') return;
       overlayNotificationsRuntime.showOverlayNotification({