docs(templates): document CRUD and model CRUD apps and expose them in mkdocs

- Add comprehensive module and function docstrings to crud_app and model_app templates
- Document OpenAPI-first guarantees, non-goals, and usage patterns in templates
- Add template-level __init__.py files with CLI and client usage examples
- Update mkdocs.yml to include CRUD and model-based CRUD template documentation
- Ensure template documentation follows strict package-bound mkdocstrings rules

openapi_first/templates/crud_app/main.py

@@ -1,3 +1,30 @@
+"""
+Application entry point for an OpenAPI-first CRUD example service.
+
+This module constructs a FastAPI application exclusively from an
+OpenAPI specification and a handler namespace, without using
+decorator-driven routing.
+
+All HTTP routes, methods, request/response schemas, and operation
+bindings are defined in the OpenAPI document referenced by
+``openapi_path``. Python callables defined in the ``routes`` module are
+bound to OpenAPI operations strictly via ``operationId``.
+
+This module contains no routing logic, persistence concerns, or
+framework configuration beyond application assembly.
+
+Design guarantees:
+- OpenAPI is the single source of truth
+- No undocumented routes can exist
+- Every OpenAPI operationId must resolve to exactly one handler
+- All contract violations fail at application startup
+
+This file is intended to be used as the ASGI entry point.
+
+Example:
+    uvicorn main:app
+"""
+
 from openapi_first.app import OpenAPIFirstApp
 import routes