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/conftest.py

@@ -5,11 +5,10 @@ pytest_plugins = ["api_server"]
 
 PROJECT_ROOT = Path(__file__).resolve().parents[1]
 SRC_PATH = PROJECT_ROOT / "src"
-LIB_PATH = PROJECT_ROOT / "lib"
 
-# Last insert(0) wins: order must be (root, lib, src) so src/models wins over
+# Last insert(0) wins: order must be (root, src) so src/models wins over
 # tests/models (same package name "models" on sys.path when pytest imports tests).
-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)