Auto mode thread questions gain an "own work" variant

In auto mode, the way Claude Code builds its thread question for projects has a third form. Before, it chose between a compact form and a compact held form, using CLAUDE_CODE_AUTO_MODE_THREAD_ASK_HELD or a remote switch. When the held form applies, a second check now chooses between it and a new held "own work" form.

That second check uses the environment variable CLAUDE_CODE_AUTO_MODE_THREAD_ASK_OWN_WORK when it is set, and a remote switch otherwise.