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.

openapi_first/codegen_routes.py

@@ -28,6 +28,9 @@ Notes:
           instead of an opaque ``payload: dict``.
         - Passing ``package=True`` writes ``<resource>/routes.py`` (with
           ``__init__.py`` sidecars) instead of a flat ``<resource>.py``.
+        - Passing ``template_style=True`` emits ``async def`` handlers whose
+          JSON body parameter is named ``body`` (matching the standards
+          template) and adds a service-resolution hint comment.
 """
 
 import re
@@ -66,6 +69,7 @@ def generate_routes(
     models_module: str = "models",
     inject_request: bool = False,
     package: bool = False,
+    template_style: bool = False,
 ) -> list[Path]:
     """
     Generate route handler stubs from an OpenAPI specification.
@@ -92,6 +96,11 @@ def generate_routes(
         package (bool, optional):
             If ``True``, emit ``<resource>/routes.py`` packages (each with an
             ``__init__.py``) instead of flat ``<resource>.py`` modules.
+        template_style (bool, optional):
+            If ``True``, emit ``async def`` handlers with a JSON body parameter
+            named ``body`` (the standards-template convention) plus a
+            service-resolution hint comment, instead of sync ``def`` handlers
+            taking ``payload``.
 
     Returns:
         list[Path]:
@@ -149,6 +158,7 @@ def generate_routes(
             use_models=use_models,
             models_module=models_module,
             inject_request=inject_request,
+            template_style=template_style,
         )
         file_path.write_text(content, encoding="utf-8")
         generated_files.append(file_path)
@@ -293,6 +303,7 @@ def _generate_resource_file(
     use_models: bool,
     models_module: str,
     inject_request: bool = False,
+    template_style: bool = False,
 ) -> str:
     """Assemble the full Python source for a single resource file."""
     op_ids = [op.get("operationId", "") for _, _, op in operations]
@@ -359,7 +370,8 @@ def _generate_resource_file(
         lines.append("")
         lines.extend(
             _generate_handler(
-                path, http_method, operation, use_models, inject_request
+                path, http_method, operation, use_models, inject_request,
+                resource, template_style,
             )
         )
 
@@ -373,10 +385,13 @@ def _generate_handler(
     operation: dict[str, Any],
     use_models: bool,
     inject_request: bool = False,
+    resource: str = "",
+    template_style: bool = False,
 ) -> list[str]:
     """Build the source lines for a single handler function."""
     operation_id = operation.get("operationId", "")
     summary = operation.get("summary", f"{http_method.upper()} {path}")
+    body_param = "body" if template_style else "payload"
 
     params: list[str] = []
     path_params: list[str] = []
@@ -424,9 +439,9 @@ def _generate_handler(
                 params.append(f"{field_name}: {annotation} = {factory}(None)")
     elif operation.get("requestBody"):
         if use_models and schema_name:
-            params.append(f"payload: {schema_name}")
+            params.append(f"{body_param}: {schema_name}")
         else:
-            params.append("payload: dict")
+            params.append(f"{body_param}: dict")
 
     # Inject Response for non-200 success codes
     success_status = _get_success_status(operation)
@@ -436,7 +451,8 @@ def _generate_handler(
     # Build function body
     lines: list[str] = []
     param_str = ", ".join(params)
-    lines.append(f"def {operation_id}({param_str}):")
+    prefix = "async def" if template_style else "def"
+    lines.append(f"{prefix} {operation_id}({param_str}):")
     lines.append(f'    """{summary}')
 
     # Document parameters
@@ -472,14 +488,20 @@ def _generate_handler(
     elif operation.get("requestBody"):
         if use_models and schema_name:
             lines.append("")
-            lines.append(f"    payload : {schema_name}")
+            lines.append(f"    {body_param} : {schema_name}")
             lines.append("        Request body.")
         else:
             lines.append("")
-            lines.append("    payload : dict")
+            lines.append(f"    {body_param} : dict")
             lines.append("        Request body.")
 
     lines.append('    """')
+    if template_style and inject_request:
+        svc_key = f"{_sanitize_identifier(resource)}_svc"
+        lines.append(
+            f'    # Resolve the service: '
+            f'request.app.state.db_resources["{svc_key}"]'
+        )
     lines.append("    raise NotImplementedError")
 
     return lines