docs: add MCP server documentation

New feature page covering architecture, available tools, local/HTTP
usage, Docker deployment, Coolify setup, dashboard management, and
example queries. Updated environment variable reference and
configuration guide with MCP_PORT. Added sidebar nav entry.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/guide/configuration.md

@@ -97,6 +97,17 @@ NVD_API_KEY=your-nvd-api-key
 
 Get a free key at [https://nvd.nist.gov/developers/request-an-api-key](https://nvd.nist.gov/developers/request-an-api-key).
 
+## MCP Server
+
+The MCP server exposes compliance data to external LLMs via the Model Context Protocol. See [MCP Server](/features/mcp-server) for full details.
+
+```bash
+# Set MCP_PORT to enable HTTP transport (omit for stdio mode)
+MCP_PORT=8090
+```
+
+The MCP server shares the `MONGODB_URI` and `MONGODB_DATABASE` variables with the rest of the platform.
+
 ## Clone Path
 
 Where the agent stores cloned repository files:
@@ -139,3 +150,4 @@ GIT_CLONE_BASE_PATH=/tmp/compliance-scanner/repos
 | `APP_URL` | No | — | Application root URL |
 | `OTEL_EXPORTER_OTLP_ENDPOINT` | No | — | OTLP collector endpoint |
 | `OTEL_SERVICE_NAME` | No | — | OpenTelemetry service name |
+| `MCP_PORT` | No | — | MCP HTTP transport port (omit for stdio) |