feat(zones): profile-scoped groups, zone modes, sequence brightness

- Optional profile_id on groups; UI and API for shared vs profile-only groups\n- Zone content_kind (presets vs sequences); edit modal shows matching sections; devices via groups only\n- Server sequence playback folds zone brightness into preset wire b (per MAC where needed)\n- Related preset/sequence/audio/beat-route and client updates

Co-authored-by: Cursor <cursoragent@cursor.com>

src/util/audio_detector.py

@@ -280,3 +280,22 @@ class AudioBeatDetector:
             with self._lock:
                 self._running = False
                 self._status["running"] = False
+
+
+# Set from ``main`` so sequence playback can tell real audio from simulated beats.
+_shared_beat_detector = None
+
+
+def set_shared_beat_detector(det):
+    global _shared_beat_detector
+    _shared_beat_detector = det
+
+
+def shared_beat_detector_running():
+    d = _shared_beat_detector
+    if d is None:
+        return False
+    try:
+        return bool(d.status().get("running"))
+    except Exception:
+        return False