Metronome/phrase click unification: run-driven beats, gated widget

- Phrase Mode (sync to metronome): the run's scheduler is the single click
  source (with count-in); the metronome widget is muted and its pendulum
  mirrors the run's beats via the new phraseBeatBus (audio-timestamp
  scheduled). No more double clicks; clicks only while the run is active
  (phraseRunBus gates the widget's own ticking).
- Schedule entries now carry continuous beat index + accent flag (downbeats
  accented, count-in beat 1 accented).
- 'At your pace': optional click via the metronome toggle (kept explicit).
- Metronome widget: gate prop; in gated mode it listens to the beat bus
  instead of running its own scheduler.

src/hooks/phraseBeatBus.ts

@@ -0,0 +1,21 @@
+/**
+ * Beat clock shared between the phrase trainer's scheduler and the global
+ * metronome widget. The phrase run emits every beat (count-in + score beats)
+ * here; the metronome widget mirrors them on its pendulum so the visual
+ * stays in sync with the audible phrase click. Beats carry an absolute
+ * AudioContext timestamp so the widget can schedule the visual swing at the
+ * right moment even when callbacks fire ahead of time.
+ */
+type BeatListener = (beat: number, at: number) => void;
+
+const listeners = new Set<BeatListener>();
+
+export const phraseBeatBus = {
+    emit(beat: number, at: number): void {
+        listeners.forEach(l => l(beat, at));
+    },
+    subscribe(l: BeatListener): () => void {
+        listeners.add(l);
+        return () => { listeners.delete(l); };
+    },
+};

src/hooks/phraseRunBus.ts

@@ -0,0 +1,26 @@
+/**
+ * Tiny pub/sub for the phrase trainer's running state.
+ *
+ * Lets the (global) metronome widget gate its pendulum/click on the phrase
+ * run: in Phrase Mode the metronome should only be active while the trainer
+ * is counting in or playing, not while idle.
+ */
+type Listener = (running: boolean) => void;
+
+const listeners = new Set<Listener>();
+let running = false;
+
+export const phraseRunBus = {
+    set(v: boolean): void {
+        if (v === running) return;
+        running = v;
+        listeners.forEach(l => l(v));
+    },
+    get(): boolean {
+        return running;
+    },
+    subscribe(l: Listener): () => void {
+        listeners.add(l);
+        return () => { listeners.delete(l); };
+    },
+};

src/hooks/usePhraseTrainer.ts

@@ -18,6 +18,8 @@ import { buildSchedule, sanitizeBpm, type ScheduleEntry } from '../game/PhraseTr
 import { PPQ } from '../score/model';
 import { audioEngine } from '../audio/AudioEngine';
 import { subscribeRawFrames } from './rawFrameBus';
+import { phraseRunBus } from './phraseRunBus';
+import { phraseBeatBus } from './phraseBeatBus';
 
 export type PhrasePhase = 'ready' | 'countIn' | 'playing' | 'paused' | 'preview' | 'done';
 
@@ -118,6 +120,9 @@ export function usePhraseTrainer(
     const setPhaseBoth = useCallback((p: PhrasePhase) => {
         phaseRef.current = p;
         setPhase(p);
+        // Expose run state so the shared metronome can gate its click/pendulum:
+        // only running during count-in and playing, never idle/preview/paused.
+        phraseRunBus.set(p === 'countIn' || p === 'playing');
     }, []);
 
     useEffect(() => { paceRef.current = config.pace; }, [config.pace]);
@@ -197,7 +202,17 @@ export function usePhraseTrainer(
                 countInBeatsRef.current > 0 &&
                 e.at <= scoreStartRef.current + 0.02;
             if ((e.kind === 'count-in-beat' || e.kind === 'beat') && !isRedundantDownbeat && configRef.current.clickSound) {
-                audioEngine.playClickAt(e.at, CLICK_VOLUME, e.kind === 'count-in-beat' ? e.beat === 0 : e.beat !== undefined);
+                audioEngine.playClickAt(e.at, CLICK_VOLUME, e.kind === 'count-in-beat' ? e.beat === 0 : e.accent === true);
+            }
+            // Publish every beat to the shared bus so the metronome widget's
+            // pendulum stays in sync with the run (click or no click).
+            if (e.kind === 'count-in-beat' || e.kind === 'beat') {
+                phraseBeatBus.emit(e.beat ?? 0, e.at);
+            }
+            // Publish every beat to the shared bus so the metronome widget's
+            // pendulum stays in sync with the run (click or no click).
+            if (e.kind === 'count-in-beat' || e.kind === 'beat') {
+                phraseBeatBus.emit(e.kind === 'count-in-beat' ? (e.beat ?? 0) : ((e.beat ?? 0) + countInBeatsRef.current), e.at);
             }
             clickIdxRef.current++;
         }