invertRecord({ a: '1', b: '2' }) // → { '1': 'a', '2': 'b' }invertRecord swaps keys and values in an object, producing the inverse mapping.
Challenge: Implement invertRecord(obj: Record<string, string>): Record<string, string> swapping each key-value pair.
invertRecord({ a: 'x', b: 'y' }) // → { x: 'a', y: 'b' }