Add batch upload configure modal and settings mapping utilities.

Users configure share mode, expiry, and max views before upload; batch summary confirms choices above the queue.

frontend/src/utils/upload/resolveUploadBatchExpiresAt.spec.ts

@@ -0,0 +1,24 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { resolveUploadBatchExpiresAt } from '@/utils/upload/resolveUploadBatchExpiresAt';
+
+describe('resolveUploadBatchExpiresAt', () => {
+    beforeEach(() => {
+        vi.useFakeTimers();
+        vi.setSystemTime(new Date('2026-01-01T12:00:00.000Z'));
+    });
+
+    afterEach(() => {
+        vi.useRealTimers();
+    });
+
+    it('returns null for never', () => {
+        expect(resolveUploadBatchExpiresAt('never')).toBeNull();
+    });
+
+    it('adds preset offsets from the reference time', () => {
+        expect(resolveUploadBatchExpiresAt('1h')).toBe('2026-01-01T13:00:00.000Z');
+        expect(resolveUploadBatchExpiresAt('24h')).toBe('2026-01-02T12:00:00.000Z');
+        expect(resolveUploadBatchExpiresAt('7d')).toBe('2026-01-08T12:00:00.000Z');
+        expect(resolveUploadBatchExpiresAt('30d')).toBe('2026-01-31T12:00:00.000Z');
+    });
+});