fix(playback): advertise only webview-decodable audio for video (DR-148, 0.4.7)

The audio codec list sent to Jellyfin comes from MediaCodecList, which
describes ExoPlayer — but video does not play through ExoPlayer. Android
force-renders every video in the webview <video> element (the interim
override in VideoPlayer.svelte) and Linux always has, and Chromium/WebKit
decode a far narrower set than the platform does.

A motorola edge 30 ships /vendor/etc/media_codecs_dolby_audio.xml, so it
reported ac3,eac3; the server direct-played an E-AC-3 track with
static=true and the webview built a video decoder and no audio decoder at
all — full picture, no sound. The defect is triggered by capability rather
than the lack of it, which is why a Fairphone and an Honor tablet play the
same file on the same build: without the Dolby decoder they never claim the
codec, so the server transcodes to AAC. Confirmed by A/B on the failing
device — hevc+eac3 silent, hevc+aac audible, same session, same profile,
same direct-play path, audio codec the only variable.

video_audio_codecs narrows the platform list to the webview-decodable set
for the video direct-play profile only. Audio-only playback really is the
native player's, so that profile keeps the full list rather than
transcoding music that plays perfectly well. A list with nothing decodable
still claims aac, since a profile claiming nothing invites the server to
give up instead of transcoding. The video codec list is deliberately
untouched: HEVC direct-plays through the webview correctly, so the
constraint is specific to audio.

Test-first: the tests failed against the old behaviour before the filter
existed, including the case built from the phone's real codec list. The
requirement-count assertion in extract-traces.test.ts moves 280 -> 281 for
the added DR, which is the deliberate edit that test exists to force.

Not yet verified on device — the 0.4.7 APK was still building.

src-tauri/src/repository/online.rs

@@ -1356,8 +1356,9 @@ impl MediaRepository for OnlineRepository {
         // Linux desktop plays video through the WebKitGTK HTML5 <video> element,
         // which cannot reliably decode HEVC/AV1/VP9. Advertise only codecs the
         // WebView can decode so Jellyfin transcodes anything else to h264 HLS.
-        // (Audio-only files still direct-play via MPV, but the PlaybackInfo
-        // profile is shared, so we keep the broadly-supported audio codecs.)
+        // (Audio-only files still direct-play via MPV; these codecs are what
+        // both renderers handle, and the audio profile keeps them in full while
+        // the video profile is narrowed below.)
         #[cfg(all(not(target_os = "android"), target_os = "linux"))]
         let (video_codecs, audio_codecs) =
             ("h264".to_string(), "aac,mp3,opus,vorbis,flac".to_string());
@@ -1368,8 +1369,19 @@ impl MediaRepository for OnlineRepository {
             "aac,mp3,opus,vorbis,flac".to_string(),
         );
 
+        // Video plays in a webview <video> element on every platform, which
+        // decodes a narrower audio set than the platform does — so the video
+        // profile must claim less than the audio-only profile. Without this a
+        // Dolby-licensed device advertises eac3, gets a direct play, and shows
+        // picture with no sound.
+        let video_audio_codecs = super::device_profile::video_audio_codecs(&audio_codecs);
+
         info!("[DeviceProfile] Using video codecs: {}", video_codecs);
         info!("[DeviceProfile] Using audio codecs: {}", audio_codecs);
+        info!(
+            "[DeviceProfile] Audio codecs for video direct play: {}",
+            video_audio_codecs
+        );
 
         // Bound every profile by what the audio route can actually voice, so a
         // multichannel track is downmixed by the server rather than direct-played
@@ -1388,12 +1400,16 @@ impl MediaRepository for OnlineRepository {
                     profile_type: "Video".to_string(),
                     container: "mp4,mkv,avi,mov,flv,ts,m2ts,webm,ogv,3gp".to_string(),
                     video_codec: Some(video_codecs.clone()),
-                    audio_codec: audio_codecs.clone(),
+                    // The webview decodes this stream, not ExoPlayer/MPV.
+                    audio_codec: video_audio_codecs.clone(),
                 },
                 DirectPlayProfile {
                     profile_type: "Audio".to_string(),
                     container: "mp3,aac,flac,alac,wav,ogg,wma,opus".to_string(),
                     video_codec: None,
+                    // Audio-only really is the native player's, so it keeps the
+                    // full platform list — narrowing it would transcode music
+                    // that plays perfectly well.
                     audio_codec: audio_codecs.clone(),
                 },
             ],