fix(api): duplicate operation id for get_image_full

There's a FastAPI bug that results in the OpenAPI spec outputting the same operation id for each operation when specifying multiple HTTP methods.

- Discussion: https://github.com/tiangolo/fastapi/discussions/8449
- Pending PR to fix: https://github.com/tiangolo/fastapi/pull/10694

In our case, we have a `get_image_full` endpoint that handles GET and HEAD.

This results in an invalid OpenAPI schema. A workaround is to use two route decorators for the operation handler. This works as expected - HEAD requests get the header, and GET requests get the resource. And the OpenAPI schema is valid.

invokeai/app/api/routers/images.py

@@ -218,9 +218,8 @@ async def get_image_workflow(
         raise HTTPException(status_code=404)
 
 
-@images_router.api_route(
+@images_router.get(
     "/i/{image_name}/full",
-    methods=["GET", "HEAD"],
     operation_id="get_image_full",
     response_class=Response,
     responses={
@@ -231,6 +230,18 @@ async def get_image_workflow(
         404: {"description": "Image not found"},
     },
 )
+@images_router.head(
+    "/i/{image_name}/full",
+    operation_id="get_image_full_head",
+    response_class=Response,
+    responses={
+        200: {
+            "description": "Return the full-resolution image",
+            "content": {"image/png": {}},
+        },
+        404: {"description": "Image not found"},
+    },
+)
 async def get_image_full(
     image_name: str = Path(description="The name of full-resolution image file to get"),
 ) -> Response: