fix(overlay): defer autoplay release for untokenized startup priming

- Autoplay-ready gate now ignores untokenized subtitle payloads while tokenization warmup is pending, so playback doesn't resume before the first tokenized cue
- Wire isTokenizationReady dep through main.ts and update gate/wiring tests accordingly
- Drop stale release/release-notes.md, add changelog entry under changes/

src/main.ts

@@ -1275,6 +1275,8 @@ const autoplayReadyGate = createAutoplayReadyGate({
   signalPluginAutoplayReady: () => {
     sendMpvCommandRuntime(appState.mpvClient, ['script-message', 'subminer-autoplay-ready']);
   },
+  // Deferred: isTokenizationWarmupReady is assigned during composeMpvRuntimeHandlers below.
+  isTokenizationReady: () => isTokenizationWarmupReady(),
   requestOverlayPointerRecovery: () => {
     if (process.platform !== 'darwin' || !overlayManager.getVisibleOverlayVisible()) {
       return;