feat: PWA update strategy with hashed assets and cache control

Move frontend sources to frontend/, build content-hashed assets at deploy,
network-first SW for shell/JS, immutable cache for /assets/, version.json
update banner, and Cache-Control middleware. Docs in docs/PWA-STRATEGY.md.

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

README.md

@@ -59,11 +59,14 @@ pip install -e .
 cp .env.example .env
 # APP_PIN und JWT_SECRET anpassen
 
-# 3. VAPID keys (für Push)
+# 3. Frontend bauen (gehashte Assets)
+python tools/build_frontend.py
+
+# 4. VAPID keys (für Push)
 python tools/gen_vapid.py
 # Output in .env eintragen
 
-# 4. Starten
+# 5. Starten
 uvicorn server.app:app --reload --host 0.0.0.0 --port 8000
 ```
 
@@ -190,14 +193,15 @@ Notification-Actions: **Genommen ✓**, **+15 Min**, **+30 Min**
 
 ```
 takeyourmeds/
+├── frontend/            # PWA-Quellen (JS, CSS, Templates)
 ├── compose.yml          # Docker + Traefik
 ├── Dockerfile
 ├── meds.yaml            # Medikamenten-Zeitplan
 ├── messages.yaml        # Humor-Pool
 ├── icon.png / icon.svg  # App-Icons (Quelle)
 ├── server/              # FastAPI Backend
-├── public/              # PWA Frontend
-├── tools/               # schema.sql, gen_vapid.py
+├── public/              # Build-Output (index.html, sw.js, assets/)
+├── tools/               # schema.sql, gen_vapid.py, build_frontend.py
 └── data/                # SQLite (gitignored)
 ```
 
@@ -207,10 +211,13 @@ takeyourmeds/
 
 ```bash
 source .venv/bin/activate
+python tools/build_frontend.py   # nach Änderungen in frontend/
 uvicorn server.app:app --reload --port 8000
 ```
 
-Service Worker cached aggressiv — für SW-Änderungen: DevTools → Application → Clear storage, oder Inkognito.
+Quellen liegen in `frontend/`; Build-Output in `public/` (gehashte JS/CSS unter `public/assets/`). PWA-Update-Strategie: `docs/PWA-STRATEGY.md`.
+
+Service Worker: bei Deploy neuer `CACHE`-Name automatisch via Build. Update-Banner erscheint bei veralteter Client-Version.
 
 ---