feat: add step-by-step visual replay and harden process lifecycle

- UI: Implement dual-mode playback in FloatingVideoPlayer supporting video and step-by-step frame replay with scrub controls and auto-fallback
- Runtime: Prevent asyncio event loop hangs on Darwin and Linux by avoiding psutil.wait_procs on direct child processes
- Task Queue: Add worker exit watchdog and automatic recording recovery for completed or interrupted sessions
- Recording: Add ffmpeg ultrafast transcode fallback, shield recording finalization against cancellation, and handle on-the-fly MP4 conversion
- Docs: Polish README_CN styling and streamline flash runner agent prompt

apps/admin_console/core/state.py

@@ -204,3 +204,9 @@ class ServerState:
 
 # Global shared instance
 state = ServerState()
+
+import sys
+if __name__ == "admin_console.core.state":
+    sys.modules["apps.admin_console.core.state"] = sys.modules[__name__]
+elif __name__ == "apps.admin_console.core.state":
+    sys.modules["admin_console.core.state"] = sys.modules[__name__]