Add per-split rest length and hands-free auto-advance flow

Two per-split settings, with the global Settings values as defaults:

- restSeconds: Int? — per-split rest, used between sets and (in flow) between
  exercises; nil falls back to the global default.
- autoAdvance: Bool? — flow mode: finishing an exercise rests, then opens the
  next one hands-free, all the way through the split.

Both are optional, snapshotted onto WorkoutDocument at the start sites (no live
split link), and not schema-bumped — same degradation pattern as activityType.

A thin RunFlowView wrapper (iOS + watch) owns the on-screen log and swaps it via
.id(currentLogID) on hand-off, so the per-exercise ExerciseProgressView stays
per-logID and untouched; the between-exercise rest reuses the existing .rest
countdown as the terminal page. The mirror reuses the per-logID live channel:
the wrapper suppresses the boundary .ended teardown so it follows across
exercises, and ContentView re-keys the cover on frame.logID — no sync-bridge
changes.

Morning Wake-Up ships as a flowing 45s-work / 15s-rest routine.

New Rest & Pacing section in the split editor exposes both controls.

Workouts Watch App/Views/WorkoutLogListView.swift

@@ -114,18 +114,17 @@ struct WorkoutLogListView: View {
             }
         }
         .navigationDestination(item: $selectedLogID) { logID in
-            ExerciseProgressView(
+            // RunFlowView hosts the run and, in a flow-mode split, auto-advances across
+            // exercises. It owns the live-run mirror wiring (incoming-frame filter,
+            // `navigatedRunID`, and the parameterized live-ended signal) since the on-screen
+            // log advances during a flowing run.
+            RunFlowView(
                 doc: $doc,
-                logID: logID,
+                startLogID: logID,
                 onChange: { bridge.update(workout: doc) },
                 onLive: { bridge.sendLiveProgress($0) },
-                onLiveEnded: { bridge.sendLiveEnded(workoutID: doc.id, logID: logID) },
-                // Follow the phone when it drives this same run from its mirror.
-                incomingFrame: bridge.liveIncoming.flatMap { $0.logID == logID ? $0 : nil }
+                sendLiveEnded: { lid in bridge.sendLiveEnded(workoutID: doc.id, logID: lid) }
             )
-            // We're driving this run inline — suppress the follower cover for it.
-            .onAppear { bridge.navigatedRunID = logID }
-            .onDisappear { if bridge.navigatedRunID == logID { bridge.navigatedRunID = nil } }
         }
         .sheet(isPresented: $showingExercisePicker) {
             ExercisePickerView(exercises: availableExercises) { exercise in