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

hexa/mcp/nav.json

@@ -0,0 +1,38 @@
+[
+  {
+    "module": "hexa",
+    "resource": "docs://modules/hexa"
+  },
+  {
+    "module": "hexa.check_matches",
+    "resource": "docs://modules/hexa.check_matches"
+  },
+  {
+    "module": "hexa.cli",
+    "resource": "docs://modules/hexa.cli"
+  },
+  {
+    "module": "hexa.container",
+    "resource": "docs://modules/hexa.container"
+  },
+  {
+    "module": "hexa.generate_abc",
+    "resource": "docs://modules/hexa.generate_abc"
+  },
+  {
+    "module": "hexa.generate_yaml",
+    "resource": "docs://modules/hexa.generate_yaml"
+  },
+  {
+    "module": "hexa.model",
+    "resource": "docs://modules/hexa.model"
+  },
+  {
+    "module": "hexa.parse_abc",
+    "resource": "docs://modules/hexa.parse_abc"
+  },
+  {
+    "module": "hexa.parse_yaml",
+    "resource": "docs://modules/hexa.parse_yaml"
+  }
+]