Add status dashboard, server, scraper stats, and DATA_DIR support

Key changes:
- Replace ratings_server.py + status.html with a unified server.py that
  serves the map, scraper status dashboard, and ratings API in one process
- Add scraper_stats.py utility: each scraper writes per-run stats (fetched,
  accepted, excluded, duration) to stats_<source>.json for the status page
- generate_status.py: respect DATA_DIR env var so status.json lands in the
  configured data directory instead of always the project root
- run_all.sh: replace the {"status":"running"} overwrite of status.json with
  a dedicated scraper_running.json lock file; trap on EXIT ensures cleanup
  even on kill/error, preventing the previous run's results from being wiped
- server.py: detect running state via scraper_running.json existence instead
  of status["status"] field, eliminating the dual-use race condition
- Makefile: add serve (local dev), debug (Docker debug container) targets;
  add SERVER_PORT variable
- build/Dockerfile + entrypoint.sh: switch to server.py, set DATA_DIR,
  adjust volume mounts
- .gitignore: add *.json and *.log to keep runtime data files out of VCS
- mapa_bytu.html: price-per-m² colouring, status link, UX tweaks

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

scrape_psn.py

@@ -15,6 +15,9 @@ import time
 from datetime import datetime
 from pathlib import Path
 from urllib.parse import urlencode
+from scraper_stats import write_stats
+
+STATS_FILE = "stats_psn.json"
 
 logger = logging.getLogger(__name__)
 
@@ -67,6 +70,8 @@ def format_price(price: int) -> str:
 
 
 def scrape(max_properties: int | None = None):
+    _run_start = time.time()
+    _run_ts = datetime.now().isoformat(timespec="seconds")
     logger.info("=" * 60)
     logger.info("Stahuji inzeráty z PSN.cz")
     logger.info(f"Cena: do {format_price(MAX_PRICE)}")
@@ -93,6 +98,15 @@ def scrape(max_properties: int | None = None):
         data = fetch_json(url)
     except Exception as e:
         logger.error(f"Chyba při stahování: {e}", exc_info=True)
+        write_stats(STATS_FILE, {
+            "source": "PSN",
+            "timestamp": _run_ts,
+            "duration_sec": round(time.time() - _run_start, 1),
+            "success": False,
+            "accepted": 0,
+            "fetched": 0,
+            "error": str(e),
+        })
         return []
 
     all_units = data.get("units", {}).get("data", [])
@@ -241,6 +255,15 @@ def scrape(max_properties: int | None = None):
     logger.info(f"  ✓ Vyhovující byty:    {len(results)}")
     logger.info(f"{'=' * 60}")
 
+    write_stats(STATS_FILE, {
+        "source": "PSN",
+        "timestamp": _run_ts,
+        "duration_sec": round(time.time() - _run_start, 1),
+        "success": True,
+        "accepted": len(results),
+        "fetched": len(all_units),
+        "excluded": excluded,
+    })
     return results
 
 
@@ -259,8 +282,22 @@ if __name__ == "__main__":
         handlers=[logging.StreamHandler()]
     )
 
+    _run_ts = datetime.now().isoformat(timespec="seconds")
     start = time.time()
-    estates = scrape(max_properties=args.max_properties)
+    try:
+        estates = scrape(max_properties=args.max_properties)
+    except Exception as e:
+        logger.error(f"Scraper failed: {e}", exc_info=True)
+        write_stats(STATS_FILE, {
+            "source": "PSN",
+            "timestamp": _run_ts,
+            "duration_sec": round(time.time() - start, 1),
+            "success": False,
+            "accepted": 0,
+            "fetched": 0,
+            "error": str(e),
+        })
+        raise
 
     if estates:
         json_path = Path("byty_psn.json")