fix: managed playback overlay lifecycle for launcher-owned sessions

- Remove --background from launcher-owned mpv starts; quit only non-tray/non-background managed sessions
- Defer autoplay-ready signal until overlay window content is loaded; retry after flush
- Retry socket availability before auto-starting overlay (up to 25 attempts, 200ms apart)
- Extract warm tokenization signal into autoplay-tokenization-warm-release with stale-media guard
- Queue second-instance commands until app ready runtime completes
- Guard globalShortcut cleanup with isAppReady check to avoid pre-ready crash
- Recognize "osx" as a macOS platform alias in Lua environment detection

src/main/runtime/autoplay-ready-gate.test.ts

@@ -143,3 +143,52 @@ test('autoplay ready gate does not unpause again after a later manual pause on t
     1,
   );
 });
+
+test('autoplay ready gate defers plugin readiness until the signal target is ready', async () => {
+  const commands: Array<Array<string | boolean>> = [];
+  let targetReady = false;
+
+  const gate = createAutoplayReadyGate({
+    isAppOwnedFlowInFlight: () => false,
+    getCurrentMediaPath: () => '/media/video.mkv',
+    getCurrentVideoPath: () => null,
+    getPlaybackPaused: () => true,
+    getMpvClient: () =>
+      ({
+        connected: true,
+        requestProperty: async () => true,
+        send: ({ command }: { command: Array<string | boolean> }) => {
+          commands.push(command);
+        },
+      }) as never,
+    signalPluginAutoplayReady: () => {
+      commands.push(['script-message', 'subminer-autoplay-ready']);
+    },
+    isSignalTargetReady: () => targetReady,
+    schedule: (callback) => {
+      queueMicrotask(callback);
+      return 1 as never;
+    },
+    logDebug: () => {},
+  });
+
+  gate.maybeSignalPluginAutoplayReady({ text: '字幕', tokens: null }, { forceWhilePaused: true });
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  assert.deepEqual(commands, []);
+
+  targetReady = true;
+  gate.flushPendingAutoplayReadySignal();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  assert.deepEqual(
+    commands.filter((command) => command[0] === 'script-message'),
+    [['script-message', 'subminer-autoplay-ready']],
+  );
+  assert.equal(
+    commands.some(
+      (command) => command[0] === 'set_property' && command[1] === 'pause' && command[2] === false,
+    ),
+    true,
+  );
+});