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/cli.py

@@ -143,6 +143,12 @@ def main() -> None:
         default=False,
         help="Emit one `<resource>/routes.py` package per resource",
     )
+    routes_parser.add_argument(
+        "--template-style",
+        action="store_true",
+        default=False,
+        help="Emit async handlers with a `body` parameter (template convention)",
+    )
 
     args = parser.parse_args()
 
@@ -167,6 +173,7 @@ def main() -> None:
                 models_module=args.models_module,
                 inject_request=args.inject_request,
                 package=args.package,
+                template_style=args.template_style,
             )
             print(f"Generated {len(files)} route file(s):")
             for f in files: