Add 4-layer access control stack (subscription → module → menu → permissions): - P1: Wire requires_permission into menu sidebar filtering - P2: Expose window.USER_PERMISSIONS for Alpine.js client-side gating - P3: Add page-level permission guards on store routes - P4: Role CRUD API endpoints and role editor UI - P5: Audit trail for all role/permission changes Includes unit tests (menu permission filtering, role CRUD service) and integration tests (role API endpoints). All 404 core+tenancy tests pass. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>