fix: sanitize settings JSON, asyncio get_running_loop, Defender exclusion, _btn cleanup, ASCII Save label

Made-with: Cursor

proxy_chain_manager/service.py

@@ -375,7 +375,7 @@ class ChainService:
     async def _build_pool(self) -> list[str]:
         """Fetch and validate proxies. Runs blocking I/O in thread pool."""
         s = self._settings
-        loop = asyncio.get_event_loop()
+        loop = asyncio.get_running_loop()
 
         # Fetch all sources concurrently in thread pool (they are blocking)
         async def _fetch_one(url: str) -> list[str]: