docs(traceability): land the DR-149 requirement rows and settle a UT collision

The DR-149 row lost an index race with a parallel session's edit of the same
file, so the previous commit carried the count assertion (DR 144, total 282)
without the requirement it counts — a clean checkout of that commit failed
`bun run test` against its own requirements.md.

The parallel session also reached UT-143 and UT-147 for subtitle work, which
collided with the UT-143 used for the client-side transcode tests. Those move
to UT-148, in the table and in the device_profile TRACES comments, so no two
requirements share an ID.

src-tauri/src/repository/device_profile.rs

@@ -102,7 +102,7 @@ pub fn video_audio_codecs(detected: &str) -> String {
 
 /// Whether the webview `<video>` element can decode this audio codec.
 ///
-/// TRACES: UR-004 | DR-149 | UT-143
+/// TRACES: UR-004 | DR-149 | UT-148
 pub fn webview_can_decode_audio(codec: &str) -> bool {
     WEBVIEW_AUDIO_CODECS
         .iter()
@@ -124,7 +124,7 @@ pub fn webview_can_decode_audio(codec: &str) -> bool {
 /// default, or the first when none is marked. An unknown codec is left alone —
 /// forcing a transcode on a guess would burn server CPU for files that play.
 ///
-/// TRACES: UR-004 | DR-149 | UT-143
+/// TRACES: UR-004 | DR-149 | UT-148
 pub fn audio_forces_transcode(streams: &[(Option<&str>, bool)]) -> bool {
     let served = streams
         .iter()