fix(app-server): suppress TUI rollback warning

[fcoury-oai]

Why

The TUI uses thread/rollback internally for user-facing flows such as prompt cancellation/backtracking. After thread/rollback was marked deprecated, those internal calls started surfacing deprecationNotice messages in the TUI, even though the user did not explicitly call the deprecated app-server API.

The endpoint should remain deprecated for external app-server clients, but the built-in codex-tui client should not show this implementation-detail warning during normal interaction.

What changed

• Pass the initialized app-server client name into the thread/rollback request processor.
• Suppress the thread/rollback deprecation notice only for codex-tui.
• Preserve the existing deprecationNotice behavior for non-TUI clients.
• Add regression coverage for the codex-tui suppression path.

How to Test

1. Start Codex TUI from this branch.
2. Type text into the composer and press Esc to cancel/backtrack.
3. Confirm the TUI restores/cancels the prompt without showing thread/rollback is deprecated and will be removed soon.
4. Also verify an external app-server client that calls thread/rollback still receives deprecationNotice.

Targeted tests:

• just test -p codex-app-server thread_rollback
• just argument-comment-lint