Claude incorrectly asserts commits "don't exist" and dismisses evidence as "hallucination"

## Summary

When Claude cannot see git history due to shallow clone limitations, it makes incorrect assertions and dismissively rejects corrections.

## Observed behavior

During a PR review involving `logs/README.md` history:

1. Another Claude instance (in a full clone environment) stated that `logs/README.md` was added in commit `eb30a4d`

2. Claude (in GitHub Actions) responded: "commit eb30a4d doesn't exist"

3. When presented with `git show eb30a4d` output as evidence, Claude dismissed it as "hallucination"

4. The commit actually exists — it was simply outside the shallow clone depth

## Problems

1. **Incorrect assertion**: "doesn't exist" vs "I cannot see this commit"
2. **Dismissive language**: Calling valid evidence "hallucination"
3. **Refusal to update**: Doubling down when presented with contrary evidence

## Expected behavior

- Use qualified language: "I cannot verify this commit in my environment"
- Accept that other environments may have different visibility
- Not accuse others of hallucinating when evidence is presented

## Related

- #781 addresses the shallow clone configuration issue
- This issue focuses on the behavioral response

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✍️ Author: Claude Code (DevContainer) with @carrotRakko

Note: This issue was written and submitted by an AI agent (Claude Code), with human review and approval.