feat: emit template-style route stubs (async, body param, service hint)

Add generate_routes(template_style=...) and CLI --template-style. When on,
stubs use async def, a JSON body parameter named body (dict or Model), and
with --inject-request a service-lookup hint comment before NotImplementedError.
Default behaviour (def/payload) unchanged. +2 tests (32 passed), wiki + MCP
bundle regenerated.

docs/wiki/03_use_cases/04_codegen.md

@@ -55,6 +55,7 @@ One file per resource (derived from the first path segment). Flags:
 | `--models-module MOD` | Dotted module for those imports (default `models`) |
 | `--inject-request` | Prepend `request: Request` to every handler (DI convention) |
 | `--package` | Emit `<resource>/routes.py` packages (with `__init__.py`) instead of flat `<resource>.py` |
+| `--template-style` | Emit `async def` handlers with a JSON body parameter named `body` (the standards-template convention) plus a service-resolution hint, instead of sync `def` handlers taking `payload` |
 
 Why bother? Because `bind_routes` (in [02 – Components](../02_components.md)) needs an `operationId` → handler **exactly** matching the spec. Codegen guarantees you never type a handler name wrong — it wears the same `operationId` the spec declares.
 
@@ -65,6 +66,15 @@ Why bother? Because `bind_routes` (in [02 – Components](../02_components.md))
 
 The stubs `raise NotImplementedError`; fill each body in (typically by resolving a service from `request.app.state`).
 
+### Handler shapes
+
+Both shapes bind equally — the router resolves the handler by `operationId` and introspects the FastAPI signature, so it never inspects the request body:
+
+- **Default (sync stub):** `def create_item(payload: ItemInput, response: Response):` — the body parameter is `payload`.
+- **`--template-style`:** `async def create_item(request: Request, body: ItemInput, response: Response):` — matches the standards template (`async def`, `body` parameter, a `request.app.state.db_resources["<resource>_svc"]` hint).
+
+Use `--template-style` when generating against the standards template so the scaffold matches the hand-written handlers you will keep.
+
 > **Note:** `models` / `routes` are build-time tooling. They do **not** run at runtime, and templates (the Bake-your-stuff section of [02 – Templates](02_templates.md)) scaffold a working server out-of-the-box for greenfield projects.
 
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