refactor(api): complete fastapi migration and related features

Finish native FastAPI controllers, drop vendored microdot, and add
Wi-Fi driver runtime, beat SSE, simulated BPM, sequence playback
improvements, bridge ESP-NOW sources, UI updates, and tests.

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

tests/test_audio_reset_tracking.py

@@ -9,7 +9,11 @@ SRC_PATH = os.path.join(PROJECT_ROOT, "src")
 if SRC_PATH not in sys.path:
     sys.path.insert(0, SRC_PATH)
 
-from util.audio_detector import AudioBeatDetector  # noqa: E402
+from util.audio_detector import (  # noqa: E402
+    AudioBeatDetector,
+    set_shared_beat_detector,
+    shared_beat_detector_timing_sequences,
+)
 
 
 class _FakeRuntime:
@@ -83,7 +87,47 @@ def test_silence_gap_starts_holdover_and_resets_tempo_once():
     det._maybe_recover_after_silence_gap(rt)
     assert rt.reset_tempo_calls == 1
     det._record_beat(120.0)
-    assert det._holdover_active is False
+    assert det._holdover_active is True
+
+
+def test_timing_sequences_true_while_holdover_active():
+    det = AudioBeatDetector()
+    set_shared_beat_detector(det)
+    try:
+        with det._lock:
+            det._running = True
+            det._status["running"] = True
+            det._status["bpm"] = 120.0
+        det._record_beat(120.0)
+        assert det._holdover_active is True
+        assert shared_beat_detector_timing_sequences() is True
+    finally:
+        set_shared_beat_detector(None)
+
+
+def test_timing_sequences_false_when_running_without_beats():
+    det = AudioBeatDetector()
+    set_shared_beat_detector(det)
+    try:
+        with det._lock:
+            det._running = True
+            det._status["running"] = True
+        assert shared_beat_detector_timing_sequences() is False
+        det._record_beat(120.0)
+        assert shared_beat_detector_timing_sequences() is True
+        det._stop_bpm_holdover()
+        with det._lock:
+            det._last_real_beat_ts = time.time() - 5.0
+        assert shared_beat_detector_timing_sequences() is False
+    finally:
+        set_shared_beat_detector(None)
+
+
+def test_record_beat_keeps_previous_bpm_when_new_readout_invalid():
+    det = AudioBeatDetector()
+    det._record_beat(128.0)
+    det._record_beat(None)
+    assert det.status()["bpm"] == 128.0
 
 
 def test_holdover_last_beat_does_not_block_tempo_retry():