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

mcp_server.py

@@ -0,0 +1,63 @@
+import json
+from pathlib import Path
+from typing import Any
+
+from config import MCPBundle
+from mcp.server.fastmcp import FastMCP
+
+
+class MCPServer:
+    """MCP server serving a pre-built documentation bundle."""
+
+    def __init__(self, bundle: MCPBundle) -> None:
+        self.mcp_root = bundle.root
+        self.app = FastMCP(
+            name=f"{bundle.name}-mcp",
+            host="0.0.0.0",
+            port=bundle.port,
+        )
+        self._register_resources()
+        self._register_tools()
+
+    # ------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------
+
+    def _read_json(self, path: Path) -> Any:
+        if not path.exists():
+            return {"error": "not_found", "path": str(path)}
+        return json.loads(path.read_text(encoding="utf-8"))
+
+    # ------------------------------------------------------------------
+    # MCP resources
+    # ------------------------------------------------------------------
+
+    def _register_resources(self) -> None:
+        @self.app.resource("doc://index")
+        def index():
+            return self._read_json(self.mcp_root / "index.json")
+
+        @self.app.resource("doc://nav")
+        def nav():
+            return self._read_json(self.mcp_root / "nav.json")
+
+        @self.app.resource("doc://modules/{module}")
+        def module(module: str):
+            return self._read_json(self.mcp_root / "modules" / f"{module}.json")
+
+    # ------------------------------------------------------------------
+    # MCP tools
+    # ------------------------------------------------------------------
+
+    def _register_tools(self) -> None:
+        @self.app.tool()
+        def ping() -> str:
+            return "pong"
+
+    # ------------------------------------------------------------------
+    # ASGI exposure
+    # ------------------------------------------------------------------
+
+    @property
+    def asgi(self):
+        return self.app