Systematically QA test a web application and fix bugs found. Runs QA testing,
then iteratively fixes bugs in source code, committing each fix atomically and
re-verifying. Use when asked to "qa", "QA", "test this site", "find bugs",
"test and fix", or "fix what's broken".
Proactively suggest when the user says a feature is ready for testing
or asks "does this work?". Three tiers: Quick (critical/high only),
Standard (+ medium), Exhaustive (+ cosmetic). Produces before/after health scores,
fix evidence, and a ship-readiness summary. For report-only mode, use /qa-only. (gstack)