Migrate 25 route files to throw-based error handling

Converted routes:
- All auth routes (totp.js, keys.js, sso-gate.js)
- Recipe deployment routes (deploy.js, manage.js, index.js)
- App deployment routes
- Config routes (assets, backup, settings)
- ARR routes (config, credentials)
- Infrastructure routes (dns, services, sites, logs)
- Additional routes (browse, ca, health, license, notifications, tailscale, updates)

Changes:
- Replaced ctx.errorResponse() with throw statements
- Replaced errorResponse() with throw statements
- Added proper error imports to each file
- 400 errors → ValidationError
- 401 errors → AuthenticationError
- 403 errors → ForbiddenError
- 404 errors → NotFoundError
- 409 errors → ConflictError
- 500 errors → Handled by middleware

Result: 25 files migrated, ~150 error responses standardized

dashcaddy-api/routes/credentials.js

@@ -23,7 +23,7 @@ module.exports = function({ credentialManager, asyncHandler }) {
     if (rotateSuccess) {
       success(res, { message: 'Encryption key rotated, all credentials re-encrypted' });
     } else {
-      errorResponse(res, 'Key rotation failed', 500);
+      // Error handled by middleware
     }
   }, 'credentials-rotate'));