feat(videos): add manual Convert button per MOV file on Pi

- New POST /api/local-video/convert route triggers queue_convert(force=True)
- queue_convert() now returns True/False/None and accepts force param
  to bypass the auto-convert toggle (manual always works)
- Convert button shown for non-MP4, non-converting files in video list
- Clicking spins the button and refreshes list after 1s to show badge

Co-authored-by: Copilot <[email protected]>

modules/app_video.py

@@ -25,20 +25,21 @@ def is_convert_enabled():
     return app_sql.get_setting(CONVERT_SETTING, "0") == "1"
 
 
-def queue_convert(relative_path):
-    """Spawn a background greenlet to re-encode relative_path to web-ready MP4.
-    No-op if conversion is disabled, already running, or file is already MP4."""
-    if not is_convert_enabled():
-        return
+def queue_convert(relative_path, force=False):
+    """Spawn a background thread to re-encode relative_path to web-ready MP4.
+    Returns True if queued, False if already converting, None if skipped (disabled/MP4).
+    Set force=True to bypass the is_convert_enabled() check (manual trigger)."""
+    if not force and not is_convert_enabled():
+        return None
     if relative_path.lower().endswith(".mp4"):
-        return
+        return None
     with _converting_lock:
         if relative_path in _converting:
-            return
+            return False
         _converting.add(relative_path)
-    gevent.sleep(0)  # yield before spawning thread
     t = threading.Thread(target=_convert_bg, args=(relative_path,), daemon=True)
     t.start()
+    return True
 
 
 def _convert_bg(relative_path):