fix: suppress unhandled rejections in retryWithBackoff failure tests

Add .catch(() => {}) before vi.runAllTimersAsync() on 3 tests that
test the rejection path — prevents vitest exit code 1 (CI/CD gate)
while still allowing .rejects assertion to work.

src/tests/retry.test.ts

@@ -37,6 +37,7 @@ describe('retryWithBackoff', () => {
 		const fn = vi.fn().mockRejectedValue(error);
 
 		const promise = retryWithBackoff(fn, { maxAttempts: 3, baseDelayMs: 10 });
+		promise.catch(() => {});
 		await vi.runAllTimersAsync();
 		await expect(promise).rejects.toThrow('persistent failure');
 		expect(fn).toHaveBeenCalledTimes(3);
@@ -102,6 +103,7 @@ describe('retryWithBackoff', () => {
 			baseDelayMs: 100,
 			onAttempt
 		});
+		promise.catch(() => {});
 		await vi.runAllTimersAsync();
 		await expect(promise).rejects.toThrow('always fail');
 		expect(fn).toHaveBeenCalledTimes(4);
@@ -119,6 +121,7 @@ describe('retryWithBackoff', () => {
 	it('defaults to 3 maxAttempts', async () => {
 		const fn = vi.fn().mockRejectedValue(new Error('fail'));
 		const promise = retryWithBackoff(fn, { baseDelayMs: 10 });
+		promise.catch(() => {});
 		await vi.runAllTimersAsync();
 		await expect(promise).rejects.toThrow('fail');
 		expect(fn).toHaveBeenCalledTimes(3);