fix: ignore reverted commit pairs

[iamhaseebn]

Thank you for reviewing.

• An issue was opened before implementation
• Tests and linter pass
• Code coverage does not decrease
• No documentation update is necessary

Summary

• Remove an unreleased commit and its matching revert from commit analysis
• Support standard This reverts commit <sha> messages and explicit Revert: <sha> footers
• Preserve reverts whose target is outside the current release range or whose abbreviated SHA is ambiguous
• Handle revert-of-revert chains so the original change is restored

Testing

• npm test - 1,216 passing
• npm run fix - 0 errors, with 21 existing warnings in unrelated files
• npm run compile

Fixes #296

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