Take @hono/node-server to 2.1.1

All three entry points we import survive the major unchanged: `serve`
keeps its `(options, listeningListener)` signature and still accepts
`fetch`, `hostname` and `port`; `RESPONSE_ALREADY_SENT` is still exported
from `utils/response`; `getConnInfo` is still on `conninfo`. The peer is
hono ^4 and the engine >=20, both of which we already meet.

What v2 adds is two defaults worth knowing about. `overrideGlobalObjects`
swaps in a lighter Request/Response, and `autoCleanupIncoming` destroys
an incoming request the app never finished reading -- which is the
behaviour you want behind a proxy, and is on by default.

Neither is something the unit tests would notice, so this was run rather
than reasoned about. Against the mock: login, an /api/events stream, and
a POST carrying a body through to upstream. The SSE path is the one that
matters, since it writes to the raw ServerResponse and hands back
RESPONSE_ALREADY_SENT; it answers with the same headers, the same
chunked encoding and the same bytes as 1.19.17 does on the same script.

server/package.json

@@ -16,7 +16,7 @@
     "mock:no-keyword-sort": "MOCK_NO_KEYWORD_SORT=1 tsx src/mock/index.ts"
   },
   "dependencies": {
-    "@hono/node-server": "^1.13.8",
+    "@hono/node-server": "^2.1.1",
     "hono": "^4.13.7"
   },
   "devDependencies": {