[Bug] AskUserQuestion tool results don't create rewind checkpoints

Bug Description
AskUserQuestion answers don't create rewind checkpoints

When Claude asks multiple questions via AskUserQuestion (even across separate assistant turns), the user's answers flow back as tool results, not as user messages. This means the Rewind UI only shows checkpoints at actual user-typed messages, not at each question/answer pair.

Expected: Each AskUserQuestion response should be a rewind-eligible checkpoint, so users can roll back to "before I answered question 3" without losing answers to questions 1 and 2.

Actual: Rewind granularity is all-or-nothing -- you can only rewind to the last user-typed message, which may be several questions ago.

Workaround attempted: Having Claude ask one question per assistant turn. Doesn't help because the rewind points are still keyed to user messages, not assistant turns containing AskUserQuestion.

Environment Info

• Platform: darwin
• Terminal: xterm-256color
• Version: 2.1.150
• Feedback ID: 6010df90-ea4b-49ce-830f-f930bfa20159

Errors

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