feat: admin audit log — merged PR #118

Audit logging for admin actions, backups, auth events.
New AuditLogPanel in Admin tab with pagination.
Dockerfile security: run as non-root user.
i18n keys for all 9 languages.

Thanks @fgbona for the implementation!

server/src/services/auditLog.ts

@@ -0,0 +1,30 @@
+import { Request } from 'express';
+import { db } from '../db/database';
+
+export function getClientIp(req: Request): string | null {
+  const xff = req.headers['x-forwarded-for'];
+  if (typeof xff === 'string') {
+    const first = xff.split(',')[0]?.trim();
+    return first || null;
+  }
+  if (Array.isArray(xff) && xff[0]) return String(xff[0]).trim() || null;
+  return req.socket?.remoteAddress || null;
+}
+
+/** Best-effort; never throws — failures are logged only. */
+export function writeAudit(entry: {
+  userId: number | null;
+  action: string;
+  resource?: string | null;
+  details?: Record<string, unknown>;
+  ip?: string | null;
+}): void {
+  try {
+    const detailsJson = entry.details && Object.keys(entry.details).length > 0 ? JSON.stringify(entry.details) : null;
+    db.prepare(
+      `INSERT INTO audit_log (user_id, action, resource, details, ip) VALUES (?, ?, ?, ?, ?)`
+    ).run(entry.userId, entry.action, entry.resource ?? null, detailsJson, entry.ip ?? null);
+  } catch (e) {
+    console.error('[audit] write failed:', e instanceof Error ? e.message : e);
+  }
+}