security(csv-export): harden mnemonic export with super admin, audit, watermark (#48)

- Add SUPER_ADMIN_IDS config (fallback to ADMIN_IDS if not set)
- Add isSuperAdmin() to middleware/auth.js
- Create auditService.js for structured audit logging (DB + pino)
- Create migration 005_audit_log.js
- Add confirmation dialog before CSV export (confirm_export_ callback)
- Check isSuperAdmin before export — block non-super admins
- Audit log every export: admin ID, wallet type, wallet count
- Add exported_by watermark column to CSV with admin telegram ID
- Notify all other super admins when export occurs
- Add SUPER_ADMIN_IDS to .env.example

8 files changed, 154 insertions, 39 deletions

.env.example

@@ -8,6 +8,7 @@
 # --- Telegram Bot ---
 BOT_TOKEN=your_bot_token_here
 ADMIN_IDS=123456789,987654321
+SUPER_ADMIN_IDS=123456789
 SUPPORT_LINK=https://t.me/your_support
 
 # --- Catalog ---