fix four audit bugs - offline playback, audio passthrough, notification dedup, dashboard fixes

src/pages/PlayerPage.tsx

@@ -291,6 +291,12 @@ export default function PlayerPage() {
   // native audioTracks switch isn't possible (transcoded streams, or
   // single-audio sources where the alternate track isn't in the file).
   // maxBitrate threads the user-picked quality cap into the same call.
+  // Offline fallback: if this item was downloaded, use the Blob URL
+  // instead of hitting the server. PlaybackInfo and reporting gracefully
+  // no-op when there's no connection.
+  const downloaded = useDownloads(s => s.getByItemId(id || ''))
+  const offlineUrl = downloaded?.status === 'done' ? downloaded.localPath : undefined
+
   const { data: playbackInfo } = usePlaybackInfo(
     id,
     startTimeTicks,
@@ -299,6 +305,7 @@ export default function PlayerPage() {
   )
   const resolvedSource = playbackInfo?.MediaSources?.[0]
   const streamUrl = (() => {
+    if (offlineUrl) return offlineUrl
     if (!resolvedSource || !serverUrl) return ''
     // Direct play: server-confirmed the browser can decode the source as-is
     if (resolvedSource.SupportsDirectPlay) {