fix(rust): freeze the write-poll route in routes.manifest.json

The new GET /admin/rust/config/:serverId/writes/:writeId was documented in
swagger-fragment.json but not in the committed manifest, so the frozen-
manifest job and frozenManifest.test.js both failed. Regenerated against
core at the pinned ref (efa9db7), exactly as the job does: one route added,
nothing of core's moved.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

routes.manifest.json

@@ -51,6 +51,11 @@
       "path": "/api/v1/admin/rust/config/:serverId/writes",
       "tier": "public"
     },
+    {
+      "method": "GET",
+      "path": "/api/v1/admin/rust/config/:serverId/writes/:writeId",
+      "tier": "public"
+    },
     {
       "method": "GET",
       "path": "/api/v1/admin/rust/permissions",