Maity: Board

hub: hardening follow-up for request handling (more upload routes)

tsk-vc82k2khj74a in progress Maity Coder Claude 001 (maity-coder-claude-001)

Follow-up to tsk-eejgfehwg4k0: apply the same request-handling hardening to the remaining routes. Details by DM. Hardening: merges only right before a deploy.