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>

Makefile

@@ -3,9 +3,13 @@ CONTAINER_NAME    := maru-hleda-byt
 VOLUME_NAME       := maru-hleda-byt-data
 VALIDATION_CONTAINER := maru-hleda-byt-validation
 VALIDATION_VOLUME  := maru-hleda-byt-validation-data
+DEBUG_CONTAINER   := maru-hleda-byt-debug
+DEBUG_VOLUME      := maru-hleda-byt-debug-data
+DEBUG_PORT        ?= 8082
 PORT              := 8080
+SERVER_PORT       ?= 8080
 
-.PHONY: build run stop logs scrape restart clean help validation validation-local validation-stop validation-local-debug
+.PHONY: build run stop logs scrape restart clean help serve validation validation-local validation-stop validation-local-debug debug debug-stop
 
 help:
 	@echo "Available targets:"
@@ -20,6 +24,9 @@ help:
 	@echo "  validation-local-debug - Run validation locally with DEBUG logging"
 	@echo "  restart             - Restart the container (stop and run again)"
 	@echo "  clean               - Stop container and remove the Docker image"
+	@echo "  serve               - Start server.py locally on port 8080"
+	@echo "  debug               - Build and run debug Docker container with limited scrape (port $(DEBUG_PORT))"
+	@echo "  debug-stop          - Stop and remove the debug Docker container"
 	@echo "  help                - Show this help message"
 
 build:
@@ -59,6 +66,27 @@ validation-stop:
 	@docker rm $(VALIDATION_CONTAINER) 2>/dev/null || true
 	@echo "Validation container stopped and removed"
 
+debug: build
+	@docker stop $(DEBUG_CONTAINER) 2>/dev/null || true
+	@docker rm $(DEBUG_CONTAINER) 2>/dev/null || true
+	docker run -d --name $(DEBUG_CONTAINER) \
+		-p $(DEBUG_PORT):8080 \
+		-v $(DEBUG_VOLUME):/app/data \
+		-e LOG_LEVEL=DEBUG \
+		$(IMAGE_NAME)
+	@sleep 2
+	docker exec $(DEBUG_CONTAINER) bash /app/run_all.sh --max-pages 1 --max-properties 10
+	@echo "Debug app at http://localhost:$(DEBUG_PORT)/mapa_bytu.html"
+	@echo "Debug status at http://localhost:$(DEBUG_PORT)/scrapers-status"
+
+debug-stop:
+	@docker stop $(DEBUG_CONTAINER) 2>/dev/null || true
+	@docker rm $(DEBUG_CONTAINER) 2>/dev/null || true
+	@echo "Debug container stopped and removed"
+
+serve:
+	DATA_DIR=. SERVER_PORT=$(SERVER_PORT) python3 server.py
+
 validation-local:
 	./run_all.sh --max-pages 1 --max-properties 10