java-quality-gate

Enforce a deterministic minimum 80% JUnit 5 line coverage (JaCoCo) and minimum 80% PITest mutation score gate on Java code. Use this whenever you finish implementing or modifying Java code in app/backend-api, whenever an OpenSpec task list includes a "run java-quality-gate" step, or whenever the user asks to write unit tests, check coverage, run mutation testing, or verify test quality for this Java codebase. Do not…