Mirror a live Apple Watch run on a propped-up iPhone

Add an ephemeral live-run presence channel (separate from the durable
iCloud progress sync) so a propped-up iPhone can mirror the Watch's
Ready → work/rest → Finish flow in real time as the user swipes.

Watch drives, phone mirrors (read-only), so there's no echo loop:
- Watch's ExerciseProgressView broadcasts a LiveProgress frame on every
  phase transition (and an ended signal on leave) via sendMessage,
  reachable-only — throwaway presence, never written to iCloud.
- Timers ride as wall-clock anchors (Date kept native in the WC dict to
  preserve sub-second precision), so both devices count independently
  off shared start times and stay in lockstep without streaming ticks.
- Phone holds a transient LiveRunState; ContentView auto-presents a
  read-only LiveProgressMirrorView full-screen cover while a run is live.

Claude-Session: https://claude.ai/code/session_01SCv7zvGFcKy47KSTnTLxRe

Workouts Watch App/Views/WorkoutLogListView.swift

@@ -86,7 +86,13 @@ struct WorkoutLogListView: View {
         }
         .navigationTitle(doc.splitName ?? Split.unnamed)
         .navigationDestination(item: $selectedLogID) { logID in
-            ExerciseProgressView(doc: $doc, logID: logID, onChange: { bridge.update(workout: doc) })
+            ExerciseProgressView(
+                doc: $doc,
+                logID: logID,
+                onChange: { bridge.update(workout: doc) },
+                onLive: { bridge.sendLiveProgress($0) },
+                onLiveEnded: { bridge.sendLiveEnded(workoutID: doc.id, logID: logID) }
+            )
         }
         .sheet(isPresented: $showingExercisePicker) {
             ExercisePickerView(exercises: availableExercises) { exercise in