chore(traceability): shift this branch's ids clear of master's

Master allocated DR-224 and UT-211 while this branch was in flight — the third
collision on this work. Everything here moves up by one: DR-224..236 become
DR-225..237, UT-211..213 become UT-212..214. UR-079, UR-080 and IR-033 were
still free and are unchanged.

Mechanical, and matched on each row's own text rather than on its number, so a
row cannot be shifted twice or the wrong one caught. Master's DR-224 (the
background-audio toggle) and UT-211 are untouched.

docs/architecture/01-rust-backend.md

@@ -675,7 +675,7 @@ source file's own bitrate, and no URL parameter afterwards can reduce it.
 
 #### Two levels of ceiling
 
-**Location**: `src-tauri/src/repository/online.rs` (TRACES: UR-074, UR-079 | DR-225)
+**Location**: `src-tauri/src/repository/online.rs` (TRACES: UR-074, UR-079 | DR-226)
 
 There are two, and they are not the same thing:
 
@@ -703,7 +703,7 @@ to constrain, or the reverse.
 ### Stream selection
 
 **Location**: `src-tauri/src/repository/stream_selection.rs`,
-`OnlineRepository::get_stream_selection` (TRACES: UR-070, UR-079 | DR-224, DR-226, DR-227)
+`OnlineRepository::get_stream_selection` (TRACES: UR-070, UR-079 | DR-225, DR-227, DR-228)
 
 **Rust decides *what stream*. The player decides *how to deliver it*.** That line
 is the whole design. A backend with genuine adaptive selection (ExoPlayer over a
@@ -719,7 +719,7 @@ the bare URL `get_video_stream_url` used to hand out:
 | `transport` | `Hls` / `Progressive` / `LocalFile` — how to fetch it |
 | `playback_kind` | `DirectPlay` / `DirectStream` / `Transcode` — what the server is doing to the source |
 | `rendition` | The negotiated ceiling and codecs; `None` for a direct play, which *is* the source |
-| `available` | The quality ladder as it applies to this media source (DR-226) |
+| `available` | The quality ladder as it applies to this media source (DR-227) |
 | `needs_transcoding` | Derived from `playback_kind`, so the rule is answered once |
 
 Both enums are serde-tagged (`{"type":"hls"}`) so the frontend matches a
@@ -777,7 +777,7 @@ a free passthrough as a server-side re-encode.
 > in its `MediaCodecList` — no Dolby licence, which is normal for a tablet — so
 > eac3 content, about a third of the sampled library, correctly transcodes there.
 > What any given device achieves depends on its own codec list, and on the
-> profile being derived from the renderer at all (DR-233), which it was not when
+> profile being derived from the renderer at all (DR-234), which it was not when
 > the figure was taken.
 >
 > **The payoff is still overwhelmingly Android**, because that is where a real
@@ -801,7 +801,7 @@ they are.
 
 #### No adaptive ladder to preserve
 
-**TRACES: UR-079 | DR-228 (Won't Do)**
+**TRACES: UR-079 | DR-229 (Won't Do)**
 
 Mid-playback re-negotiation on throughput was scoped and dropped on measurement.
 A master playlist from this server carries exactly **one** `EXT-X-STREAM-INF`: