feat(standards): integrate auth-server via pinned spec (docs://spec) + auth recipe and template slice

- serve the pinned auth-server OpenAPI contract as the standards MCP resource docs://spec (no auth-server MCP bundle)
- add Auth Integration recipe (14) and wire it into the registry, prompts, index, and nav
- un-defer Auth Server in the library registry (spec/recipe pointers)
- ship the opt-in template auth slice: interfaces/auth/ (placeholder + mergeable bearerAuth security.yaml) and AUTH_SERVER/JWT_SERVER env
- rebuild bundle (13 modules, 44 components); template stays authless by default

standards/mcp/index.json

@@ -1,6 +1,6 @@
 {
   "project": "standards",
   "type": "standards",
-  "modules_count": 12,
+  "modules_count": 13,
   "source": "hand-authored"
 }