Unify server, persist ratings via API, refresh scraper data

- Replace split setup (ratings_server.py on :8081 + http.server on :8080)
  with a single combined Flask server (server.py) on :8080 that serves
  static files and the /api/ratings GET/POST endpoints
- Ratings are now persisted server-side: mapa_bytu.html loads ratings
  from GET /api/ratings on startup (API as source of truth) and POSTs
  on every change — enables cross-browser and cross-device state sharing
  while keeping localStorage as a synchronous read cache
- Dockerfile: install flask, copy server.py instead of ratings_server.py,
  expose only port 8080
- entrypoint.sh: start single server process instead of two
- Makefile: add serve / serve-debug targets for local development
- scrape_psn.py: fix log label, add --max-pages stub arg for CLI parity
- Refresh all scraped property data

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

project/todo.md

@@ -11,4 +11,9 @@
 
 
 ## documentation
-- precisely document original intent of the app (Maru has to provide this)
+- precisely document original intent of the app (Maru has to provide this)
+
+##
+- prepare production run
+    - probably in home kubernetes
+    - maru-hleda-byt.lab.home.hrajfrisbee.cz