refactor(server): bundle worker pipeline into PipelineState

Group the four worker handles (analyze/transcribe x busy/tx) into a
new PipelineState struct with a FromRef<AppState> impl. Convert
heal_orphans_if_idle from a free function with 6 parameters into a
method on PipelineState. The two web handlers (handle_my_cases,
handle_case_detail) now take one State<PipelineState> instead of
four separate State extractors.

The original FromRef impls for AnalyzeBusy/Sender and TranscribeBusy/
Sender remain intact so handlers that need only one of them keep
their narrower signature.

server/src/lib.rs

@@ -51,6 +51,20 @@ impl Drop for BusyGuard {
     }
 }
 
+/// Bundle of the four worker-pipeline handles (analyze + transcribe,
+/// each with a busy-flag and a job sender). Extracted so handlers that
+/// need the whole pipeline (self-heal, status probes) can take a single
+/// `State<PipelineState>` instead of four separate `State(...)` params.
+/// The individual `FromRef<AppState>` impls below remain valid, so
+/// handlers that only need one sender keep their narrower signature.
+#[derive(Clone)]
+pub struct PipelineState {
+    pub analyze_busy: AnalyzeBusy,
+    pub analyze_tx: AnalyzeSender,
+    pub transcribe_busy: TranscribeBusy,
+    pub transcribe_tx: TranscribeSender,
+}
+
 /// Shared application state. Clonable — all fields are cheap to clone
 /// (`Arc` and `mpsc::Sender`).
 #[derive(Clone)]
@@ -99,6 +113,17 @@ impl FromRef<AppState> for TranscribeBusy {
     }
 }
 
+impl FromRef<AppState> for PipelineState {
+    fn from_ref(state: &AppState) -> Self {
+        PipelineState {
+            analyze_busy: state.analyze_busy.clone(),
+            analyze_tx: state.analyze_tx.clone(),
+            transcribe_busy: state.transcribe_busy.clone(),
+            transcribe_tx: state.transcribe_tx.clone(),
+        }
+    }
+}
+
 /// Test/simple entrypoint: jobs pushed into either channel are dropped
 /// because the receivers are not retained. Use [`create_router_with_state`]
 /// from `main.rs` where real workers own the receivers.