Phase 1: Add ESLint/Prettier config + baseline auto-fixes

dashcaddy-api/__tests__/backup-manager.test.js

@@ -198,7 +198,7 @@ describe('cleanupOldBackups', () => {
         name: 'daily',
         status: 'success',
         timestamp: new Date(Date.now() - i * 86400000).toISOString(),
-        locations: [{ type: 'local', path: `/tmp/fake-${i}.backup` }]
+        locations: [{ type: 'local', path: `/tmp/fake-${i}.backup` }],
       });
     }