feat: remove manual db transaction begin/commit from rpc message handler

The diff removes explicit `self.app.db.begin()` and `self.app.db.commit()` calls from the RPC message processing loop in `src/snek/view/rpc.py`, suggesting transaction management is now handled elsewhere or implicitly.

src/snek/view/rpc.py

@@ -203,9 +203,7 @@ class RPCView(BaseView):
             if msg.type == web.WSMsgType.TEXT:
                 try:
                     async with Profiler():
-                        self.app.db.begin()
                         await rpc(msg.json())
-                        self.app.db.commit()
                 except Exception as ex:
                     print(ex, flush=True)
                     await self.services.socket.delete(ws)