uploadFile mutation in AI chat uses wrong Apollo client (sends to /graphql instead of /metadata)
File uploads in the AI chat (Agent Chat) fail with "Failed to upload file: [filename]" for all file
types.
Root Cause:
useAIChatFileUpload.ts explicitly passes useApolloCoreClient() as the Apollo client for
useUploadFileMutation. The "core" client points to the /graphql (workspace) endpoint. However,
FileUploadResolver is decorated with @MetadataResolver(), meaning uploadFile is only registered on the
/metadata endpoint.