app-server README uses stale conversation_id for feedback/upload

What happened?

The app-server README describes feedback/upload as accepting conversation_id:

classification + optional reason/logs, conversation_id, and optional extraLogFiles

The current protocol uses camelCase threadId instead:

pub thread_id: Option<String>

The processor also reads thread_id from FeedbackUploadParams.

Expected behavior

The app-server README should refer to threadId rather than conversation_id when documenting feedback/upload.

Additional context

I searched open issues and PRs for terms including feedback/upload, conversation_id, threadId, and app-server README, and did not find an existing open item that appears to cover this documentation mismatch.