chore: add stats DB cleanup and gitignore

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

.gitignore

@@ -1 +1,2 @@
 .worktrees
+civitai_stats.db

proxy.py

@@ -625,11 +625,14 @@ async def lm_remote_proxy_middleware(request: web.Request, handler):
 
 
 async def _cleanup_proxy_session(app) -> None:
-    """Shutdown hook to close the shared proxy session."""
-    global _proxy_session
+    """Shutdown hook to close the shared proxy session and stats DB."""
+    global _proxy_session, _stats_db
     if _proxy_session and not _proxy_session.closed:
         await _proxy_session.close()
         _proxy_session = None
+    if _stats_db:
+        _stats_db.close()
+        _stats_db = None
 
 
 def register_proxy(app) -> None: