v0.9.0 — 494 unit tests + 98% coverage + real gate classes

494 unit tests + ~98% python coverage for the harness's own 15 scripts (the audits' #1 test-adequacy gap). Coverage/SAST/supply-chain/shellcheck gate classes wired. Two real bugs the tests found (stop-loop INTEGRITY masking; mutate bytecode-cache flake) fixed. Cross-task laundering (verdict_state ignored task_id) fixed + task-scoped. macOS mktemp test-portability fixed.