feat(ui): add message cache management page and dashboard enhancements

- Introduced MessageCachePage for browsing and managing cached webhook events.
- Enhanced DashboardPage to display runtime stats and message cache information.
- Added new API types for message cache events and system stats.
- Integrated SwaggerPage for API documentation and live request testing.

config/config.example.json

@@ -114,5 +114,12 @@
     "file_dir": "./data/events",
     "table_name": "event_logs"
   },
+  "message_cache": {
+    "enabled": true,
+    "storage": "database",
+    "data_path": "./data/message_cache",
+    "max_age_days": 7,
+    "max_events": 10000
+  },
   "log_level": "info"
 }