test: add atomicity regression tests for UPDATE/DELETE failures

[aviralgarg05]

Summary

Add integration tests for UPDATE/DELETE atomicity when WHERE evaluation fails.

Why

Executor uses two-phase logic to prevent partial writes/deletes; this guarantee should be locked in with regression tests.

Tasks

• Add integration tests in tests/integration_test.rs
• Create failure case where WHERE evaluation errors
• Assert no partial updates/deletions occur

Acceptance Criteria

• Failing WHERE path leaves data unchanged
• Tests fail on regression and pass in current implementation
• Assertions cover both UPDATE and DELETE

[coderabbitai]

🔗 Related PRs

#57 - feat: Add DELETE statement support with WHERE clause filtering [merged]
#59 - feat: Add UPDATE statement support [merged]
#137 - feat: add transaction support (BEGIN/COMMIT/ROLLBACK) with WAL recovery [merged]

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[KUMARI-SONALIUPADHYAY]

Hi @maintainers 👋

I would like to work on this issue as part of OSCG.
Could you please assign it to me?

Thank you 🙂