Summary

• adds focused Vitest coverage for QueryLogPlugin failure paths
• verifies addQuery swallows insert failures and returns []
• verifies expireLog returns false and logs when deletion fails

Related issue

Part of #71

Verification

• pnpm vitest run plugins/query-log/index.test.ts
• pnpm exec prettier --check plugins/query-log/index.test.ts
• git diff --check

Notes

• pnpm test run currently has existing failures in src/rls/index.test.ts on main (4 RLS policy assertion failures). The query-log test file itself passes locally: 10/10.

/claim #71