v0.6.4 — Adversarial QA Phase 3–8: all phases complete

Bug Fixes (Phases 3–8)

Phase 3 (DB concurrency): 20 concurrent writes passed, WAL mode verified, schema collision idempotent.

Phase 4 (SQL injection): 15 injection payloads across cron/loop/split — all rejected safely, no tables dropped.

Phase 6 (infrastructure failures):

• read-only DB: unhandled sqlite3.OperationalError now caught in main() with user-friendly message (#335)

Phase 8 (--json coverage):

• budget check --json with no budget: now returns {"budget": null, "unlimited": true} instead of plain text (#336)
• queue-dep list: new subcommand to list DAG jobs with status (#337)
• security --json top-level: added --json to parent parser so security --json works without specifying scan (#338)
• queue-dep promote --json: added JSON output
• Final sweep: 27/27 --json paths verified valid JSON