refactor(audit): extract audit domain into self-contained module

Move the entire audit subsystem (system audit, API audit, import audit,
user lifecycle audit, frontend telemetry) from core into modules/audit/.

Core decoupling via interface-based injection:
- AuditRecorderInterface replaces SystemAuditService in 10+ core services
- UserLifecycleAuditInterface / ImportAuditInterface for specialized flows
- NullAuditRecorder fallback when audit module is disabled
- ApiBootstrap/ApiResponse use null-safe callable resolvers

Module structure (modules/audit/):
- Manifest with routes, permissions, scheduler jobs, authorization policy
- 9 services, 8 repositories, 6 domain enums, 4 job handlers
- 33 page files, 4 JS files, 8 test files, migration scripts, i18n

Core cleanup:
- OperationsAuthorizationPolicy, UiCapabilityMap, PermissionService
  surgically cleaned of audit-specific constants
- Sidebar template cleared of hardcoded audit navigation
- AuditModuleIsolationContractTest ensures no future core→module coupling

All quality gates pass: 1346 tests (19,276 assertions), PHPStan level 5
clean, architecture contracts verified.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/notifications/web/js/components/app-notification-bell.js

@@ -122,8 +122,8 @@ export function initNotificationBell(root = document, config = {}) {
                 `<span class="app-notification-item__time">${escapeHtml(timeAgo(n.created))}</span>` +
             `</div>` +
             `<div class="app-notification-item__actions">` +
-                (n.is_read === 0 ? `<button type="button" class="app-notification-item__action-btn" data-action="mark-read" title="${escapeHtml(dropdown.dataset.labelMarkRead || '')}"><i class="bi bi-check2"></i></button>` : '') +
-                `<button type="button" class="app-notification-item__action-btn" data-action="dismiss" title="${escapeHtml(dropdown.dataset.labelDismiss || '')}"><i class="bi bi-x"></i></button>` +
+                (n.is_read === 0 ? `<button type="button" class="app-notification-item__action-btn" data-action="mark-read" title="${escapeHtml(dropdown.dataset.labelMarkRead || '')}" aria-label="${escapeHtml(dropdown.dataset.labelMarkRead || '')}"><i class="bi bi-check2"></i></button>` : '') +
+                `<button type="button" class="app-notification-item__action-btn" data-action="dismiss" title="${escapeHtml(dropdown.dataset.labelDismiss || '')}" aria-label="${escapeHtml(dropdown.dataset.labelDismiss || '')}"><i class="bi bi-x"></i></button>` +
             `</div>`;
 
         // Keyboard + click navigation for items with a link