Fix feedback 401 (persist quickconnect_code); silence benign Kivy Image error

- player_auth.py: save quickconnect_code in auth_data during authenticate() so
  send_feedback() no longer posts quickconnect_code=null (was returning 401 on
  POST /api/player-feedback while /api/auth/verify returned 200). Also carry it
  through clear_auth() defaults.
- main.py: Logger.setLevel('Image', 'CRITICAL') to silence the harmless
  "Image: Error loading <file.mp4>" logged by Kivy's Video widget, which
  subclasses Image and runs the image loader before the ffpyplayer video load.

src/main.py

@@ -60,6 +60,12 @@ from kivy.core.window import Window
 from kivy.properties import BooleanProperty
 from kivy.logger import Logger
 
+# Kivy's Video widget subclasses Image, so its inherited image loader always
+# runs first and logs a harmless "Image: Error loading <file.mp4>" for every
+# video (the real decoding is done by the ffpyplayer CoreVideo provider).
+# Silence just that logger so genuine errors stay visible.
+Logger.setLevel('Image', 'CRITICAL')
+
 # Try to import evdev for card reader support (after Logger is available)
 try:
     import evdev

src/player_auth.py

@@ -121,6 +121,9 @@ class PlayerAuth:
                 self.auth_data = {
                     'hostname': hostname,
                     'auth_code': data.get('auth_code'),
+                    # Persist the quick-connect code: the feedback endpoint
+                    # requires it in the request body (see send_feedback).
+                    'quickconnect_code': quickconnect_code,
                     'player_id': data.get('player_id'),
                     'player_name': data.get('player_name'),
                     'playlist_id': data.get('playlist_id'),
@@ -354,6 +357,7 @@ class PlayerAuth:
         self.auth_data = {
             'hostname': self.auth_data.get('hostname', ''),
             'auth_code': '',
+            'quickconnect_code': self.auth_data.get('quickconnect_code', ''),
             'player_id': None,
             'player_name': '',
             'playlist_id': None,