docs, cli: enforce package-bound docs, add template scaffolding, and document CLI usage

- Restrict mkdocstrings generation to real Python packages (require __init__.py)
- Add explicit documentation section for CLI scaffolding and templates
- Generalize CLI to support multiple templates with dynamic discovery
- Package templates correctly for importlib.resources access
- Add fully documented health_app template (app entry point and handlers)
- Fix setuptools package-data configuration for bundled templates

These changes make documentation import-safe, clarify package boundaries,
and provide a deterministic, OpenAPI-first scaffolding workflow via CLI.

openapi_first/__init__.py

@@ -49,6 +49,32 @@ Runtime dependencies are intentionally minimal:
 The ASGI server (e.g., uvicorn) is an application-level dependency and is
 not bundled with this library.
 
+----------------------------------------------------------------------
+Command-Line Interface (Scaffolding, Templates)
+----------------------------------------------------------------------
+
+FastAPI OpenAPI First ships with a small CLI for bootstrapping
+OpenAPI-first FastAPI applications from bundled templates.
+
+List available application templates:
+
+    openapi-first --list
+
+Create a new application using the default template:
+
+    openapi-first
+
+Create a new application using a specific template:
+
+    openapi-first health_app
+
+Create a new application in a custom directory:
+
+    openapi-first health_app my-service
+
+The CLI copies template files verbatim into the target directory.
+No code is generated or modified beyond the copied scaffold.
+
 ----------------------------------------------------------------------
 Server-Side Usage (OpenAPI → FastAPI)
 ----------------------------------------------------------------------