fix: comprehensive security, bug, performance, and UI/UX audit

Security
- Default bind 127.0.0.1; first-run bootstrap generates random api_token
  and refuses to bind non-loopback without auth unless explicitly opted in
- Path-traversal hardened: BrowserService.validate_path rejects absolute
  paths, drive letters, UNC, NUL bytes. /api/browser/{play,metadata,
  thumbnail} now require folder_id and a folder-relative path
- Pydantic validators on links: http(s) URLs only, mdi:<slug> icons only
- Scripts/callbacks/links create/update/delete gated by *_management flags
- Strict CSP, X-Frame-Options DENY, Referrer-Policy no-referrer,
  X-Content-Type-Options nosniff
- CORS locked to localhost:<port> + 127.0.0.1:<port> by default; configurable
- config.yaml writes atomic (tmp + os.replace) and 0o600 on POSIX
- Subprocesses spawned in their own process group / new session so timeout
  kills the whole tree (Windows CREATE_NEW_PROCESS_GROUP, POSIX
  start_new_session=True)
- Frontend XSS: monitor name + details escapeHtml'd; power button moved to
  delegated data-action handler; remote MDI SVGs parsed and sanitized
  (strip script/foreignObject/on*/javascript: hrefs) before innerHTML
- All dynamic URL segments now wrapped in encodeURIComponent

Bugs
- WebSocket reconnect: close previous socket before opening new, clear
  ping interval per-socket, clear reconnectTimeout up-front, retry on
  online/visibilitychange, try/catch JSON.parse
- Artwork fetch race: AbortController + generation guard
- _broadcast_after_open: initialize status, swallow per-poll errors,
  background tasks tracked in a strong-ref set with done-callback cleanup
- Audio analyzer: sticky _unavailable flag prevents infinite start/stop
  spin when no loopback device exists; cleared by set_device()
- Volume short-circuit cache invalidated when server reports remote volume
- Browser thumbnail race: per-folder generation counter + isConnected
  checks; aborts in-flight fetches on navigation
- Track-skip uses cached title instead of full WinRT status round-trip

Performance
- Linux MPRIS/pactl and /api/display DDC-CI handlers wrapped in
  asyncio.to_thread so blocking IO never stalls the event loop
- browse_directory moved off the event loop (SMB shares could freeze it)
- Windows status poll caches one asyncio loop per worker thread via
  threading.local instead of new_event_loop/close on every 0.5s tick
- broadcast() serializes JSON once and uses send_text to all clients
- Hourly thumbnail cache cleanup scheduled in lifespan (was never invoked
  — cache grew unbounded)
- Progress drag listeners attached only while dragging

Quality
- All asyncio.get_event_loop() in coroutines → get_running_loop()
- ThreadPoolExecutors shut down cleanly during lifespan teardown
- config_manager dedup: 12 near-identical methods collapsed onto generic
  _upsert/_delete helpers (~290 lines removed)
- Service worker no longer pass-throughs every fetch
- M3U playlist written via NamedTemporaryFile (no fixed-path symlink
  clobber race)
- __version__ now prefers live pyproject.toml in dev checkouts so
  pip install -e . users see the source-of-truth version, not the stale
  package-metadata version baked in at install time

UI/UX (Studio Reference)
- Green leftover focus rings (rgba(29,185,84,...)) all replaced with
  copper accent (rgba(var(--copper-rgb),...))
- Dialogs: square corners, copper top hairline, unified with editorial
  chrome
- .browser-item: transparent with copper hover border (was filled card)
- Audio device select uses var(--sans) instead of generic system font
- Mobile container padding tuned for ≤480px screens
- Breadcrumb home is a real <button> with aria-label; aria-current on root
- i18n: filled display.msg.power_*, execution.*, scripts.params.execute,
  callbacks.empty in both en + ru

media_server/services/linux_media.py

@@ -151,22 +151,19 @@ class LinuxMediaController(MediaController):
             logger.error(f"Failed to toggle mute: {e}")
             return False
 
-    async def get_status(self) -> MediaStatus:
-        """Get current media playback status."""
+    def _sync_get_status(self) -> MediaStatus:
+        """Synchronous status read (called from a worker thread)."""
         status = MediaStatus()
 
-        # Get system volume
         volume, muted = self._get_volume_pulseaudio()
         status.volume = volume
         status.muted = muted
 
-        # Get active player
         player_name = self._get_active_player()
         if player_name is None:
             status.state = MediaState.IDLE
             return status
 
-        # Get playback status
         playback_status = self._get_property(player_name, "PlaybackStatus")
         if playback_status == "Playing":
             status.state = MediaState.PLAYING
@@ -177,114 +174,70 @@ class LinuxMediaController(MediaController):
         else:
             status.state = MediaState.IDLE
 
-        # Get metadata
         metadata = self._get_property(player_name, "Metadata")
         if metadata:
             status.title = str(metadata.get("xesam:title", "")) or None
-
             artists = metadata.get("xesam:artist", [])
             if artists:
                 status.artist = str(artists[0]) if isinstance(artists, list) else str(artists)
-
             status.album = str(metadata.get("xesam:album", "")) or None
             status.album_art_url = str(metadata.get("mpris:artUrl", "")) or None
-
-            # Duration in microseconds
             length = metadata.get("mpris:length", 0)
             if length:
                 status.duration = int(length) / 1_000_000
 
-        # Get position (in microseconds)
         position = self._get_property(player_name, "Position")
         if position is not None:
             status.position = int(position) / 1_000_000
 
-        # Get source name
         status.source = player_name.replace(self.MPRIS_PREFIX, "")
-
         return status
 
-    async def play(self) -> bool:
-        """Resume playback."""
+    async def get_status(self) -> MediaStatus:
+        """Get current media playback status (off the event loop)."""
+        # pactl + DBus calls each take 5-100ms on a Pi and would block every
+        # other coroutine on the server. Run them in a worker thread.
+        return await asyncio.to_thread(self._sync_get_status)
+
+    def _call_player(self, method_name: str) -> bool:
         player_name = self._get_active_player()
         if player_name is None:
             return False
         try:
             player = self._get_player_interface(player_name)
-            player.Play()
+            getattr(player, method_name)()
             return True
         except Exception as e:
-            logger.error(f"Failed to play: {e}")
+            logger.error(f"Failed to call player.{method_name}: {e}")
             return False
 
+    async def play(self) -> bool:
+        return await asyncio.to_thread(self._call_player, "Play")
+
     async def pause(self) -> bool:
-        """Pause playback."""
-        player_name = self._get_active_player()
-        if player_name is None:
-            return False
-        try:
-            player = self._get_player_interface(player_name)
-            player.Pause()
-            return True
-        except Exception as e:
-            logger.error(f"Failed to pause: {e}")
-            return False
+        return await asyncio.to_thread(self._call_player, "Pause")
 
     async def stop(self) -> bool:
-        """Stop playback."""
-        player_name = self._get_active_player()
-        if player_name is None:
-            return False
-        try:
-            player = self._get_player_interface(player_name)
-            player.Stop()
-            return True
-        except Exception as e:
-            logger.error(f"Failed to stop: {e}")
-            return False
+        return await asyncio.to_thread(self._call_player, "Stop")
 
     async def next_track(self) -> bool:
-        """Skip to next track."""
-        player_name = self._get_active_player()
-        if player_name is None:
-            return False
-        try:
-            player = self._get_player_interface(player_name)
-            player.Next()
-            return True
-        except Exception as e:
-            logger.error(f"Failed to skip next: {e}")
-            return False
+        return await asyncio.to_thread(self._call_player, "Next")
 
     async def previous_track(self) -> bool:
-        """Go to previous track."""
-        player_name = self._get_active_player()
-        if player_name is None:
-            return False
-        try:
-            player = self._get_player_interface(player_name)
-            player.Previous()
-            return True
-        except Exception as e:
-            logger.error(f"Failed to skip previous: {e}")
-            return False
+        return await asyncio.to_thread(self._call_player, "Previous")
 
     async def set_volume(self, volume: int) -> bool:
-        """Set system volume."""
-        return self._set_volume_pulseaudio(volume)
+        return await asyncio.to_thread(self._set_volume_pulseaudio, volume)
 
     async def toggle_mute(self) -> bool:
-        """Toggle mute state."""
-        return self._toggle_mute_pulseaudio()
+        return await asyncio.to_thread(self._toggle_mute_pulseaudio)
 
-    async def seek(self, position: float) -> bool:
-        """Seek to position in seconds."""
+    def _sync_seek(self, position: float) -> bool:
         player_name = self._get_active_player()
         if player_name is None:
             return False
         try:
             player = self._get_player_interface(player_name)
-            # MPRIS expects position in microseconds
             player.SetPosition(
                 self._get_property(player_name, "Metadata").get("mpris:trackid", "/"),
                 int(position * 1_000_000),
@@ -294,6 +247,9 @@ class LinuxMediaController(MediaController):
             logger.error(f"Failed to seek: {e}")
             return False
 
+    async def seek(self, position: float) -> bool:
+        return await asyncio.to_thread(self._sync_seek, position)
+
     async def open_file(self, file_path: str) -> bool:
         """Open a media file with the default system player (Linux).