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/api_server.py

@@ -14,9 +14,8 @@ from starlette.testclient import TestClient
 
 PROJECT_ROOT = Path(__file__).resolve().parents[1]
 SRC_PATH = PROJECT_ROOT / "src"
-LIB_PATH = PROJECT_ROOT / "lib"
 
-for p in (str(PROJECT_ROOT), str(LIB_PATH), str(SRC_PATH)):
+for p in (str(PROJECT_ROOT), str(SRC_PATH)):
     if p in sys.path:
         sys.path.remove(p)
     sys.path.insert(0, p)
@@ -81,7 +80,7 @@ def server(monkeypatch, tmp_path_factory):
     tmp_db_dir = tmp_root / "db"
     tmp_settings_file = tmp_root / "settings.json"
 
-    for p in (str(SRC_PATH), str(LIB_PATH), str(PROJECT_ROOT)):
+    for p in (str(SRC_PATH), str(PROJECT_ROOT)):
         if p in sys.path:
             sys.path.remove(p)
         sys.path.insert(0, p)