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

main.py

@@ -15,7 +15,7 @@ from http.server import BaseHTTPRequestHandler, HTTPServer
 from pathlib import Path
 
 from config import MCPBundle, load_config
-from core import MCPServer
+from mcp_server import MCPServer
 from registry import StandardsMCPServer
 
 APP_ROOT = Path(__file__).resolve().parent