Add compliance audit log

Immutable audit_log table in the scanner DB records every significant
admin action (profile save/delete, token create/revoke, PIN changes,
source add/update/delete, scheduler job changes, scan start/stop, SMTP
save, dispositions, item delete/redact). GET /api/audit_log exposes
entries newest-first. New Audit Log tab in the Settings modal renders
the table on demand. Settings modal widened 540→640 px and tab labels
set to white-space:nowrap so the six-tab row fits on one line.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lang/en.json

@@ -675,6 +675,14 @@
   "m365_settings_tab_general": "General",
   "m365_settings_tab_email": "Email report",
   "m365_settings_tab_database": "Database",
+  "m365_settings_tab_auditlog": "Audit Log",
+  "m365_audit_title": "Compliance Audit Log",
+  "m365_audit_col_time": "Time",
+  "m365_audit_col_action": "Action",
+  "m365_audit_col_detail": "Detail",
+  "m365_audit_col_ip": "IP",
+  "m365_audit_loading": "Loading…",
+  "m365_audit_empty": "No audit events recorded yet.",
   "m365_settings_appearance": "Appearance",
   "m365_settings_language": "Language",
   "m365_settings_theme": "Theme",