refactor: restructure CLI and improve documentation/typing

- Consolidated CLI commands into [build](cci:1://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/mkdocs/logic.py:48:0-58:46) and [serve](cci:1://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/commands.py:70:0-92:32) using `--mkdocs` and `--mcp` flags.
- Separated CLI orchestration logic into [docforge/cli/mkdocs/logic.py](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/mkdocs/logic.py:0:0-0:0) and [docforge/cli/mcp/logic.py](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/mcp/logic.py:0:0-0:0).
- Moved command definitions to [docforge/cli/commands.py](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/commands.py:0:0-0:0), making [main.py](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/main.py:0:0-0:0) a thin entry point.
- Aligned [.pyi](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/docforge/cli/main.pyi:0:0-0:0) type stubs with [.py](cci:7://file:///c:/Users/vishe/WorkSpace/code/aetos/doc-forge/tests/conftest.py:0:0-0:0) implementations across the package.
- Added missing docstrings to internal helper functions and core classes.
- Restructured tests into `tests/mkdocs/` and `tests/mcp/`.
- Updated navigation specification to reflect the new project structure.

tests/cli/test_serve_mcp.py

@@ -0,0 +1,17 @@
+from docforge.cli.main import cli
+
+def test_mcp_serve(
+    cli_runner,
+    fake_mcp_docs,
+    mock_mcp_server_run,
+    monkeypatch,
+):
+    monkeypatch.chdir(fake_mcp_docs.parent)
+
+    result = cli_runner.invoke(
+        cli,
+        ["serve", "--mcp", "--out-dir", str(fake_mcp_docs)],
+    )
+
+    assert result.exit_code == 0
+    assert mock_mcp_server_run()