feat(mcp): add MCP JSON renderer and CLI support, update tests accordingly

- Add MCPRenderer to generate MCP-native JSON bundles (index.json, nav.json, modules/*.json)
- Expose MCPRenderer via public API and CLI (`generate-mcp` command)
- Replace Markdown-based MCP output with structured JSON resources
- Update MCP renderer type stubs to match new JSON-based implementation
- Refactor MCP tests to validate JSON content, bundle structure, and navigation
- Fix MCP module coverage test to use explicit project_root for reliable discovery

docforge/cli/main.py

@@ -9,7 +9,7 @@ from typing import Sequence, Optional
 import click
 
 from docforge.loaders import GriffeLoader, discover_module_paths
-from docforge.renderers.mkdocs_renderer import MkDocsRenderer
+from docforge.renderers import MkDocsRenderer, MCPRenderer
 from docforge.cli.mkdocs import mkdocs_cmd
 
 
@@ -118,6 +118,52 @@ def generate(
     click.echo(f"Documentation sources generated in {docs_dir}")
 
 
+# ---------------------------------------------------------------------
+# mcp-build
+# ---------------------------------------------------------------------
+
+@cli.command(name="generate-mcp")
+@click.option(
+    "--module",
+    required=True,
+    help="Python module import path to document",
+)
+@click.option(
+    "--project-name",
+    help="Project name (defaults to first module)",
+)
+@click.option(
+    "--out-dir",
+    type=click.Path(path_type=Path),
+    default=Path("mcp_docs"),
+)
+def generate_mcp(
+    module: str,
+    project_name: str | None,
+    out_dir: Path,
+) -> None:
+    """
+    Generate MCP-compatible documentation resources for the specified module.
+
+    Args:
+        module: The primary module path to document.
+        project_name: Optional project name override.
+        out_dir: Directory where MCP resources will be written.
+    """
+    loader = GriffeLoader()
+    discovered_paths = discover_module_paths(module)
+
+    project = loader.load_project(
+        discovered_paths,
+        project_name,
+    )
+
+    renderer = MCPRenderer()
+    renderer.generate_sources(project, out_dir)
+
+    click.echo(f"MCP documentation resources generated in {out_dir}")
+
+
 # ---------------------------------------------------------------------
 # build
 # ---------------------------------------------------------------------