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>

scrape_psn.py

@@ -234,7 +234,7 @@ def scrape(max_properties: int | None = None):
 
     logger.info(f"\n{'=' * 60}")
     logger.info(f"Výsledky PSN:")
-    logger.info(f"  Staženo jednotek:      {len(all_units)}")
+    logger.info(f"  Staženo inzerátů:      {len(all_units)}")
     for reason, count in excluded.items():
         if count:
             logger.info(f"  Vyloučeno ({reason}): {count}")
@@ -246,6 +246,8 @@ def scrape(max_properties: int | None = None):
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(description="Scrape apartments from PSN.cz")
+    parser.add_argument("--max-pages", type=int, default=None,
+                        help="Ignored — PSN uses a single API call, no pagination")
     parser.add_argument("--max-properties", type=int, default=None,
                         help="Maximum number of properties to include in results")
     parser.add_argument("--log-level", type=str, default="INFO",