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.

mcp_docs/nav.json

@@ -7,14 +7,30 @@
     "module": "docforge.cli",
     "resource": "doc://modules/docforge.cli"
   },
+  {
+    "module": "docforge.cli.commands",
+    "resource": "doc://modules/docforge.cli.commands"
+  },
   {
     "module": "docforge.cli.main",
     "resource": "doc://modules/docforge.cli.main"
   },
+  {
+    "module": "docforge.cli.mcp",
+    "resource": "doc://modules/docforge.cli.mcp"
+  },
+  {
+    "module": "docforge.cli.mcp.logic",
+    "resource": "doc://modules/docforge.cli.mcp.logic"
+  },
   {
     "module": "docforge.cli.mkdocs",
     "resource": "doc://modules/docforge.cli.mkdocs"
   },
+  {
+    "module": "docforge.cli.mkdocs.logic",
+    "resource": "doc://modules/docforge.cli.mkdocs.logic"
+  },
   {
     "module": "docforge.loaders",
     "resource": "doc://modules/docforge.loaders"