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/test_crud_app.py

@@ -3,11 +3,20 @@ End-to-end tests for the OpenAPI-first CRUD example app.
 
 These tests validate that all CRUD operations behave correctly
 against the in-memory mock data store.
+- OpenAPI specification loading
+- OperationId-driven route binding on the server
+- OperationId-driven client invocation
+- Correct HTTP status codes and response payloads
+
+The tests exercise all CRUD operations against an in-memory mock data
+store and assume deterministic behavior within a single process.
 
 The tests assume:
 - OpenAPI-first route binding
 - In-memory storage (no persistence guarantees)
 - Deterministic behavior in a single process
+- One-to-one correspondence between OpenAPI operationId values and
+  server/client callables
 """
 
 from fastapi.testclient import TestClient