docs: bring docforge docstrings and wiki to GSDFC standard

- fix GSDFC spec contradictions in __init__ docstring (parenthesized types, fenced-block rule) and sync generated README
- rewrite docstrings across loaders, models, nav, servers, renderers, cli; sync .pyi stubs
- add pydoclint (google style) gate to dev extras and pyproject config
- fix mcp nav resources doc:// -> docs://
- refresh docs/lib and docs/mcp, drop stale docforge/ duplicate group
- update wiki pages and add GSDFC + MCP guides under 05_development

docforge/cli/commands.py

@@ -4,6 +4,15 @@
 Command definitions for the doc-forge CLI.
 
 Provides the CLI structure using Click, including build, serve, and tree commands.
+
+---
+
+Notes:
+    - The `build` command validates requested modes before generating anything.
+    - `--mkdocs`, `--api`, and `--wiki` share a single MkDocs build; `--mcp`
+      generates a machine-readable bundle independently.
+
+---
 """
 
 from pathlib import Path
@@ -12,6 +21,7 @@ import click
 
 from docforge.cli import api_utils, mcp_utils, mkdocs_utils
 from docforge.loaders import GriffeLoader
+from docforge.models import DocObject
 
 
 @click.group()
@@ -99,9 +109,9 @@ def build(
     """
     Build documentation artifacts.
 
-    This command performs the full documentation build pipeline:
-    style of the selected platform, generates renderer-specific
-    documentation sources, and optionally builds the final output.
+    This command runs the full documentation pipeline: it loads Python
+    modules, generates renderer-specific documentation sources, and
+    optionally builds or serves the final output.
 
     Depending on the selected options, the build can target:
 
@@ -110,6 +120,12 @@ def build(
     - Hand-written wiki pages included in the MkDocs site
     - MCP structured documentation resources
 
+    Notes:
+        - At least one of `--mcp`, `--mkdocs`, `--wiki`, or `--api` must be
+          provided.
+        - `--mkdocs`, `--api`, and `--wiki` are combined into a single MkDocs
+          build, while `--mcp` emits a machine-readable bundle.
+
     Args:
         mcp (bool):
             Enable MCP documentation generation.
@@ -126,16 +142,16 @@ def build(
         module_is_source (bool):
             Treat the specified module directory as the project root.
 
-        module (Optional[str]):
+        module (str | None):
             Python module import path to document.
 
-        openapi_spec (Optional[Path]):
+        openapi_spec (Path | None):
             Path to the OpenAPI JSON specification used for API docs.
 
-        project_name (Optional[str]):
+        project_name (str | None):
             Optional override for the project name.
 
-        site_name (Optional[str]):
+        site_name (str | None):
             Display name for the MkDocs site.
 
         docs_dir (Path):
@@ -147,7 +163,7 @@ def build(
         nav_file (Path):
             Path to the navigation specification file.
 
-        template (Optional[Path]):
+        template (Path | None):
             Optional custom MkDocs configuration template.
 
         mkdocs_yml (Path):
@@ -282,7 +298,7 @@ def serve(
         mkdocs (bool):
             Serve the MkDocs development site.
 
-        module (Optional[str]):
+        module (str | None):
             Python module import path to serve via MCP.
 
         mkdocs_yml (Path):
@@ -333,7 +349,7 @@ def tree(
         module (str):
             Python module import path to introspect.
 
-        project_name (Optional[str]):
+        project_name (str | None):
             Optional name to display as the project root.
     """
     loader = GriffeLoader()
@@ -347,7 +363,7 @@ def tree(
             _print_object(obj, indent="│   ")
 
 
-def _print_object(obj, indent: str) -> None:
+def _print_object(obj: DocObject, indent: str) -> None:
     """
     Recursively print a documentation object and its members.
 
@@ -355,7 +371,7 @@ def _print_object(obj, indent: str) -> None:
     and prints each object with indentation to represent hierarchy.
 
     Args:
-        obj:
+        obj (DocObject):
             Documentation object to print.
 
         indent (str):