fix(swarm): inject peer cert into ASGI scope for uvicorn <= 0.44

Uvicorn's h11/httptools HTTP protocols don't populate scope['extensions']['tls'], so /swarm/heartbeat's per-request cert pinning was 403ing every call despite CERT_REQUIRED validating the cert at handshake. Patch RequestResponseCycle.__init__ on both protocol modules to read the peer cert off the asyncio transport and write DER bytes into scope['extensions']['tls']['client_cert_chain']. Importing the module from swarm_api.py auto-installs the patch in the swarmctl uvicorn worker before any request is served.

decnet/web/swarm_api.py

@@ -16,6 +16,8 @@ shared DB.
 """
 from __future__ import annotations
 
+from decnet.web import _uvicorn_tls_scope  # noqa: F401  # patches uvicorn on import
+
 from contextlib import asynccontextmanager
 from typing import AsyncGenerator