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/browse.js

@@ -82,7 +82,7 @@ module.exports = function(ctx) {
           ip: req.ip,
           userAgent: req.get('user-agent')
         });
-        return ctx.errorResponse(res, 403, 'Access denied - path traversal detected');
+        throw new ForbiddenError('Access denied - path traversal detected');
       }
       throw error;
     }
@@ -94,7 +94,7 @@ module.exports = function(ctx) {
 
     const stats = await fsp.stat(resolvedPath);
     if (!stats.isDirectory()) {
-      return ctx.errorResponse(res, 400, 'Path is not a directory');
+      throw new ValidationError('Path is not a directory');
     }
 
     const entries = await fsp.readdir(resolvedPath, { withFileTypes: true });