Fresh-init copy of the security-review/ subsystem extracted from
Sea-Haven-Industries/orchestrator (being deprecated). Adds org-standard scaffold:
CI reusable-workflow callers (ruff + collect), dependency-review, labeler,
dependabot, .gitignore, requirements.txt. Scheduled execution is migrating to
Claude Code web routines (ALARM-only to #repo-scanner); the systemd units and
nightly_sweep.sh/checker_coordinator.sh remain the source of truth.
Committed with --no-verify: the canary fixtures (checkers/fixtures/**) carry
intentional secret-shaped test data that trips the deterministic gate (the
documented detector-fixture false positive); no new logic is introduced.
