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

nginx.conf

@@ -5,6 +5,10 @@ server {
     root /usr/share/nginx/html;
     index index.html lib/index.html api/index.html;
 
+    location ~ ^/[^/]+/mcp/ {
+        deny all;
+    }
+
     location / {
         try_files $uri $uri/ /index.html;
     }