refactor: serve MCP bundles under <name>/mcp with nginx guard; rename core->mcp_server

- collect.py: copy repo MCP bundles to ROOT/<name>/mcp (instead of ROOT/mcp/<name>); add nginx location guard to deny /<name>/mcp/
- config.py: bundle roots now point to <repo>/mcp and standards/mcp for static bundles
- Rename core.py -> mcp_server.py and update imports in main.py and registry.py
- Dockerfile: per-repo MCP COPYs under /app/<name>/mcp, drop blog copy; add ports 8008/8009 in .drone.yml
- Restore standards/mcp/libraries.json from git for registry server

registry.py

@@ -19,7 +19,7 @@ from pathlib import Path
 from typing import Any
 
 from config import MCPBundle
-from core import MCPServer
+from mcp_server import MCPServer
 
 
 class StandardsMCPServer(MCPServer):