fix(mobile): stop user messages subscribing to thread updates

[kvnloo]

Every rendered user message calls useThreadSelection() only to recover the current threadId when opening a document attachment. Because the selected thread shell is replaced as activity streams in, each historical user row subscribes to those updates and re-renders during active turns.

ThreadFeed already owns the exact threadId. Pass it through renderFeedEntry into UserMessageContent and use that value for attachment navigation instead of subscribing each row to the live thread shell.

This addresses the user-row re-render source identified in #14010. Markdown measurement and feed derivation remain separate concerns.

Local native execution is not available from this connector-only session, so this is opened as a draft for CI verification.

Refs #14010.

Model: GPT-5.6 Sol. Harness: ChatGPT.

[juliusmarminge]

Note

This comment is posted by Julius' dot

This follows the accepted user-row scope in #14010, but the PR reports no executed verification and current checks contain only label jobs. There is no observed result showing that row updates decrease or that attachment navigation still uses the correct thread. Please provide a focused render-count check and attachment-navigation results, as required by verification, then request reconsideration.