refactor(api): migrate server to fastapi and uvicorn

Replace the Microdot-only entrypoint with a CombinedASGI app that
handles FastAPI routes (audio API, websocket, dev live-reload) while
delegating the rest to Microdot. Suppress noisy /__dev/ access logs
during live-reload polling.

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

README.md

@@ -11,8 +11,8 @@ LED controller web app for managing profiles, **zones**, presets, and colour pal
 ## Run
 
 - One-time setup for port 80 without root: `sudo scripts/setup-port80.sh`
-- Start app: `pipenv run run` (override listen port with the **`PORT`** environment variable)
-- Dev watcher (auto-restart on `src/` changes): `pipenv run dev`
+- Start app: `pipenv run run` (FastAPI + uvicorn; override listen port with **`PORT`**)
+- Dev mode (uvicorn **`--reload`** on `src/` + browser refresh via `dev-live-reload.js`): `pipenv run dev`
 - Regenerate **`docs/help.pdf`** from **`docs/help.md`**: `pipenv run help-pdf` (requires **pandoc** and **chromium** on the host)
 
 ## UI modes