chore: restore the TypedDict annotations dropped in the rebuild and keep size nullable in the spliced schema

The rebuilt branch missed the writable-ok annotations on
ImageVariationRequestParams (LIT012) and still needs mutable-ok on the
two OpenAPI fixture dicts (LIT001); the spliced ImageResponse.size also
kept its nullable branch, which the regeneration includes.

litellm/proxy/_lazy_openapi_snapshot.json

@@ -22712,6 +22712,9 @@
                     "1536x1024"
                   ],
                   "type": "string"
+                },
+                {
+                  "type": "null"
                 }
               ],
               "title": "Size"

litellm/proxy/image_endpoints/endpoints.py

@@ -53,7 +53,7 @@ IMAGE_VARIATION_OPTIONAL_FIELD_DEFAULTS: Final = MappingProxyType({"image": None
 # ImageVariationRequestParams carries FileTypes (typing.IO[bytes]) which
 # pydantic cannot turn into a JSON schema, so the documented JSON body
 # schema is spelled out for the shape the multipart form accepts.
-_IMAGE_VARIATION_REQUEST_BODY: Final[dict[str, object]] = {
+_IMAGE_VARIATION_REQUEST_BODY: Final[dict[str, object]] = {  # mutable-ok: OpenAPI JSON fixture, never mutated
     "required": True,
     "content": {
         "application/json": {
@@ -71,7 +71,9 @@ _IMAGE_VARIATION_REQUEST_BODY: Final[dict[str, object]] = {
         }
     },
 }
-_IMAGE_VARIATION_OPENAPI_EXTRA: Final[dict[str, object]] = {"requestBody": _IMAGE_VARIATION_REQUEST_BODY}
+_IMAGE_VARIATION_OPENAPI_EXTRA: Final[dict[str, object]] = {  # mutable-ok: handed to FastAPI which copies openapi_extra
+    "requestBody": _IMAGE_VARIATION_REQUEST_BODY
+}
 
 IMAGE_ARRAY_FIELD: Final = "image[]"
 MASK_ARRAY_FIELD: Final = "mask[]"

litellm/types/images/main.py

@@ -42,5 +42,5 @@ class ImageVariationRequestParams(ImageEditOptionalRequestParams, total=False):
     Params here: https://platform.openai.com/docs/api-reference/images/createVariation
     """
 
-    image: FileTypes
-    model: str | None
+    image: FileTypes  # writable-ok: request params mirror ImageEditRequestParams' mutable wire format
+    model: str | None  # writable-ok: request params mirror ImageEditRequestParams' mutable wire format