[codex] Address post-merge review feedback

[explicit09]

Summary

• Addresses late Codex review feedback left on merged PRs [codex] Fix changed clip ID merge contract #26 and [codex] Add multi-author commit attribution #28.
• Preserves explicit author as the primary author when deserializing mixed-format commit JSON.
• Fixes changed-clip-ID merge edge cases:
  • unidentified clips now count toward positional move detection,
  • consecutive trailing source changes keep source order,
  • stale transitions/gaps adjacent to source-deleted clips are removed.

Review Threads Addressed

• [codex] Fix changed clip ID merge contract #26: [codex] Fix changed clip ID merge contract #26 (comment)
• [codex] Fix changed clip ID merge contract #26: [codex] Fix changed clip ID merge contract #26 (comment)
• [codex] Fix changed clip ID merge contract #26: [codex] Fix changed clip ID merge contract #26 (comment)
• [codex] Add multi-author commit attribution #28: [codex] Add multi-author commit attribution #28 (comment)

Validation

• Added regression tests that failed before the fixes.
• cargo test

[explicit09]

@codex

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Can't wait for the next one!

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".