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/health.js

@@ -229,7 +229,7 @@ module.exports = function({
   router.get('/health/probe', asyncHandler(async (req, res) => {
     const targetUrl = req.query.url;
     if (!targetUrl) {
-      return errorResponse(res, 'Missing ?url= parameter', 400);
+      throw new ValidationError('Missing ?url= parameter');
     }
     const result = await checkDirect(targetUrl);
     res.json(result || {