feat(audio-sequences): beat phase sync and aligned playback

Add bar-phase tracking, audio reset/anchor APIs, BPM holdover, beat-phase
sequence switching, sync-phase endpoint, and sample sequence data.

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

src/controllers/settings.py

@@ -4,10 +4,10 @@ import json
 from microdot import Microdot, send_file
 
 from models import wifi_ws_clients
-from settings import Settings
+from settings import get_settings
 
 controller = Microdot()
-settings = Settings()
+settings = get_settings()
 
 @controller.get('')
 async def get_settings(request):
@@ -75,7 +75,21 @@ def _validate_global_brightness(value):
     return v
 
 
-@controller.put('/settings')
+def _validate_sequence_switch_wait(value):
+    s = str(value).strip().lower()
+    if s not in ("beat", "downbeat"):
+        raise ValueError("sequence_switch_wait must be beat or downbeat")
+    return s
+
+
+def _validate_audio_beat_phase_ms(value):
+    v = int(value)
+    if v < 0 or v > 500:
+        raise ValueError("audio_beat_phase_ms must be between 0 and 500")
+    return v
+
+
+@controller.put('')
 async def update_settings(request):
     """Update general settings."""
     try:
@@ -87,6 +101,10 @@ async def update_settings(request):
             elif key == 'global_brightness' and value is not None:
                 settings[key] = _validate_global_brightness(value)
                 global_brightness_changed = True
+            elif key == 'sequence_switch_wait' and value is not None:
+                settings[key] = _validate_sequence_switch_wait(value)
+            elif key == 'audio_beat_phase_ms' and value is not None:
+                settings[key] = _validate_audio_beat_phase_ms(value)
             else:
                 settings[key] = value
         settings.save()