feat: implement background scheduler for job scraping with Gunicorn support

gunicorn.conf.py

@@ -36,3 +36,17 @@ certfile = None
 # Application
 wsgi_module = "web.app:app"
 callable = "app"
+
+
+def when_ready(server):
+	"""Start background scheduler once in Gunicorn master if enabled."""
+	import os
+	flag = (os.environ.get("SCRAPE_SCHEDULER_ENABLED") or "").strip().lower()
+	if flag not in {"1", "true", "yes", "on"}:
+		return
+	try:
+		from web.craigslist import start_scheduler_in_background
+		start_scheduler_in_background()
+		server.log.info("Background scraper scheduler started in Gunicorn master.")
+	except Exception as exc:
+		server.log.warning("Failed to start background scraper scheduler: %s", exc)