feat(observability): implement global database error logging, Prometheus error metrics, and max 3-panel Grafana dashboard

services/publisher.py

@@ -9,6 +9,7 @@ from db.repository import Repository
 from core.queue import RedisQueue
 from core.metrics import TARGET_ACTIVITY_TOTAL, QUEUE_POSTS_GAUGE, REDIS_QUEUE_SIZE_GAUGE
 from core.proxy import get_telegram_proxy
+from core.error_logger import log_exception
 
 logger = logging.getLogger(__name__)
 
@@ -129,7 +130,7 @@ class PublisherService:
                 TARGET_ACTIVITY_TOTAL.labels(channel_id=str(target.channel_id), title=target.title or '').inc()
                 logger.info(f"Published post ID {post_id} to Target {target.title} ({target.channel_id})")
             except Exception as e:
-                logger.error(f"Failed to publish queued post {post_id} to target {target.channel_id}: {e}", exc_info=True)
+                await log_exception("publisher.publish", e, {"post_id": post_id, "target_id": target.id, "channel_id": target.channel_id})
 
         REDIS_QUEUE_SIZE_GAUGE.set(total_queued)