docs(player): allocate UR-074/DR-162 for the streaming bitrate cap

The feature shipped tagged against DR-160, which a parallel session had
claimed for picture-in-picture in the meantime. Renumbered to DR-162
across the Rust and frontend TRACES comments (the PiP tags in
VideoPlayer.svelte, pictureInPicture.ts and nativeVideo.ts keep DR-160)
and regenerated bindings.ts.

Adds the requirement rows the tags point at: UR-074 for the user need, and
DR-162 covering why the cap has to reach the PlaybackInfo negotiation and
not only the transcode URL, why the ceiling is process-wide, and why the
Settings default persists while the in-player override does not. Notes
that this gives UR-070 its resume-at-the-same-point mechanism while the
server-offered rendition list that requirement also asks for stays
proposed. UT-156/157 record what the tests pin.

docs/specs/streaming-bitrate-cap.md carries the layer assignment — the
step definitions, the video/audio split, the resolution pairing and the
reload decision are all Rust; the frontend holds a serde token and the
labels it was handed.

TRACES: UR-074 | DR-162 | UT-156, UT-157

src-tauri/src/repository/online.rs

@@ -23,7 +23,7 @@ use crate::utils::lock::RwLockSafe;
 /// Set from `player_set_video_settings` / `player_set_stream_quality`, and
 /// restored from the database at startup.
 ///
-/// TRACES: UR-074 | DR-160
+/// TRACES: UR-074 | DR-162
 static STREAMING_QUALITY: RwLock<StreamingQuality> = RwLock::new(StreamingQuality::Original);
 
 /// Apply a bandwidth ceiling to every subsequently-opened video stream.
@@ -32,14 +32,14 @@ static STREAMING_QUALITY: RwLock<StreamingQuality> = RwLock::new(StreamingQualit
 /// property of the URL the server is transcoding for, so changing it mid-stream
 /// requires re-opening at the new quality (`player_set_stream_quality`).
 ///
-/// TRACES: UR-074 | DR-160
+/// TRACES: UR-074 | DR-162
 pub fn set_streaming_quality(quality: StreamingQuality) {
     *STREAMING_QUALITY.write_safe() = quality;
 }
 
 /// The ceiling currently applied to new video streams.
 ///
-/// TRACES: UR-074 | DR-160
+/// TRACES: UR-074 | DR-162
 pub fn streaming_quality() -> StreamingQuality {
     *STREAMING_QUALITY.read_safe()
 }
@@ -421,7 +421,7 @@ impl OnlineRepository {
     /// that suits the budget. `Original` keeps the historical 20/18 Mbps
     /// allowance, which is a transcode ceiling rather than a user-facing limit.
     ///
-    /// TRACES: UR-004, UR-074 | DR-140, DR-160 | UT-130, UT-156
+    /// TRACES: UR-004, UR-074 | DR-140, DR-162 | UT-130, UT-156
     pub async fn get_video_stream_url(
         &self,
         item_id: &str,
@@ -537,7 +537,7 @@ impl OnlineRepository {
             // Audio-only is already far under any video cap, but a user on the
             // bottom rungs of the ladder asked for *less traffic*, so take the
             // lower of the two rather than always 384 kbps.
-            // TRACES: UR-074 | DR-160
+            // TRACES: UR-074 | DR-162
             (
                 "MaxStreamingBitrate",
                 streaming_quality().audio_bitrate().min(384_000).to_string(),
@@ -1473,7 +1473,7 @@ impl MediaRepository for OnlineRepository {
         // downstream is moot. `Original` keeps the historical "no ceiling"
         // sentinel so the default path negotiates exactly as before.
         //
-        // TRACES: UR-074 | DR-160
+        // TRACES: UR-074 | DR-162
         let quality = streaming_quality();
         let negotiated_bitrate = quality.max_bitrate().unwrap_or(999_999_999) as i64;
         if let Some(cap) = quality.max_bitrate() {
@@ -1714,7 +1714,7 @@ impl MediaRepository for OnlineRepository {
             is_playback: true,
             // Live TV is video like any other, so the user's cap applies here
             // too — a channel opened at the source bitrate would walk straight
-            // past a limit set for the connection. TRACES: UR-074 | DR-160
+            // past a limit set for the connection. TRACES: UR-074 | DR-162
             max_streaming_bitrate: streaming_quality().max_bitrate().unwrap_or(20_000_000),
         };
 
@@ -2466,7 +2466,7 @@ mod tests {
     /// streaming ceiling, and restores the uncapped default afterwards — without
     /// it, a capped test running concurrently changes what an uncapped one sees.
     ///
-    /// TRACES: UR-074 | DR-160
+    /// TRACES: UR-074 | DR-162
     static QUALITY_LOCK: std::sync::Mutex<()> = std::sync::Mutex::new(());
 
     struct QualityFixture(#[allow(dead_code)] std::sync::MutexGuard<'static, ()>);
@@ -2490,7 +2490,7 @@ mod tests {
     /// can carry. Capping only `MaxStreamingBitrate` would leave the server
     /// encoding 1080p into 2 Mbps.
     ///
-    /// TRACES: UR-074 | DR-160 | UT-156
+    /// TRACES: UR-074 | DR-162 | UT-156
     #[tokio::test]
     async fn test_video_stream_url_applies_bitrate_cap() {
         let _fixture = QualityFixture::set(StreamingQuality::Mbps2);
@@ -2512,7 +2512,7 @@ mod tests {
     /// The uncapped default must keep the exact transcode allowance this
     /// endpoint has always used, and must not start constraining resolution.
     ///
-    /// TRACES: UR-074 | DR-160 | UT-156
+    /// TRACES: UR-074 | DR-162 | UT-156
     #[tokio::test]
     async fn test_video_stream_url_uncapped_keeps_legacy_allowance() {
         let _fixture = QualityFixture::set(StreamingQuality::Original);
@@ -2535,7 +2535,7 @@ mod tests {
     /// The background-audio handoff is already cheap, but someone who capped the
     /// connection at 720 kbps asked for less traffic than its fixed 384 kbps.
     ///
-    /// TRACES: UR-040, UR-074 | DR-160 | UT-156
+    /// TRACES: UR-040, UR-074 | DR-162 | UT-156
     #[tokio::test]
     async fn test_audio_only_stream_url_takes_the_lower_of_cap_and_default() {
         {