feat(stats): wire stats server, overlay, and CLI into main process

- Stats server auto-start on immersion tracker init
- Stats overlay toggle via keybinding and IPC
- Stats CLI command (subminer stats) with cleanup mode
- mpv plugin menu integration for stats toggle
- CLI args for --stats, --stats-cleanup, --stats-response-path

src/main/runtime/mpv-main-event-bindings.test.ts

@@ -48,6 +48,7 @@ test('main mpv event binder wires callbacks through to runtime deps', () => {
     notifyImmersionTitleUpdate: (title) => calls.push(`notify-title:${title}`),
 
     recordPlaybackPosition: (time) => calls.push(`time-pos:${time}`),
+    recordMediaDuration: (duration) => calls.push(`duration:${duration}`),
     reportJellyfinRemoteProgress: (forceImmediate) =>
       calls.push(`progress:${forceImmediate ? 'force' : 'normal'}`),
     recordPauseState: (paused) => calls.push(`pause:${paused ? 'yes' : 'no'}`),