fix(proxy): correct stale image_generation route label, drop inert type:ignore

ROUTE_ENDPOINT_MAPPING has mapped aimage_generation to the singular
/image/generations since 2024, but every registered route is plural
(/v1/images/generations, /images/generations, .../images/generations). The
new missing-prompt guard surfaced this stale label for the first time, so
correct it to /images/generations. Also drop two # type: ignore[override]
comments added in the new image_generation regression test: basedpyright's
enableTypeIgnoreComments is false here, so they suppressed nothing.

litellm/proxy/route_llm_request.py

@@ -77,7 +77,7 @@ ROUTE_ENDPOINT_MAPPING: Final = {
     "acompletion": "/chat/completions",
     "atext_completion": "/completions",
     "aembedding": "/embeddings",
-    "aimage_generation": "/image/generations",
+    "aimage_generation": "/images/generations",
     "aspeech": "/audio/speech",
     "atranscription": "/audio/transcriptions",
     "amoderation": "/moderations",

tests/test_litellm/proxy/image_endpoints/test_endpoints.py

@@ -129,14 +129,14 @@ async def test_image_generation__missing_required_param_is_400(monkeypatch):
     async def fake_add_litellm_data_to_request(**kwargs):
         return kwargs["data"]
 
-    async def fake_pre_call_hook(*, user_api_key_dict, data, call_type):  # type: ignore[override]
+    async def fake_pre_call_hook(*, user_api_key_dict, data, call_type):
         return data
 
     async def fake_post_call_failure_hook(**_: Any) -> None:
         return None
 
-    async def fake_route_request(*, data, **kwargs):  # type: ignore[override]
-        raise ProxyMissingRequiredParamError(route="/image/generations", param="prompt")
+    async def fake_route_request(*, data, **kwargs):
+        raise ProxyMissingRequiredParamError(route="/images/generations", param="prompt")
 
     fake_proxy_logger = SimpleNamespace(
         pre_call_hook=fake_pre_call_hook,

tests/test_litellm/proxy/test_route_llm_request.py

@@ -1048,7 +1048,7 @@ async def test_route_request_override_enable_tag_filtering_beats_body_value():
         ("acreate_batch", "input_file_id", "/batches"),
         ("aspeech", "input", "/audio/speech"),
         ("amoderation", "input", "/moderations"),
-        ("aimage_generation", "prompt", "/image/generations"),
+        ("aimage_generation", "prompt", "/images/generations"),
     ],
 )
 @pytest.mark.parametrize(