refactor: rename loader/model packages to loaders/models

- Rename docforge.loader → docforge.loaders and docforge.model → docforge.models
- Update all imports, type stubs, CLI, tests, and documentation references
- Align MkDocs navigation and docforge.nav.yml with new package structure
- Adjust module docstrings and comments for consistency with pluralized naming

tests/renderers/test_mkdocs_module_coverage.py

@@ -1,6 +1,6 @@
 from pathlib import Path
 
-from docforge.loader import GriffeLoader, discover_module_paths
+from docforge.loaders import GriffeLoader, discover_module_paths
 from docforge.renderers.mkdocs import MkDocsRenderer
 
 
@@ -41,21 +41,21 @@ def test_mkdocs_emits_all_modules(tmp_path: Path) -> None:
     # expected = {
     #     'docforge/cli/main.md',
     #     'docforge/renderers/index.md',
-    #     'docforge/loader/index.md',
-    #     'docforge/model/index.md',
+    #     'docforge/loaders/index.md',
+    #     'docforge/models/index.md',
     #     'docforge/nav/index.md',
     #     'docforge/renderers/mkdocs.md',
     #     'docforge/index.md',
-    #     'docforge/loader/griffe_loader.md',
-    #     'docforge/model/object.md',
+    #     'docforge/loaders/griffe_loader.md',
+    #     'docforge/models/object.md',
     #     'docforge/cli/index.md',
     #     'docforge/nav/resolver.md',
     #     'docforge/renderers/base.md',
     #     'docforge/nav/mkdocs.md',
     #     'docforge/nav/spec.md',
-    #     'docforge/model/module.md',
+    #     'docforge/models/module.md',
     #     'docforge/cli/mkdocs.md',
-    #     'docforge/model/project.md'
+    #     'docforge/models/project.md'
     # }
     missing = expected - emitted
     assert not missing, f"Missing markdown files for modules: {missing}"