## Root Cause
The `DateTimePicker` component lazy-loads `react-datepicker` using
React's `lazy()` with a `Suspense` fallback that shows skeleton loaders:
```typescript
const ReactDatePicker = lazy<ComponentType<DatePickerPropsType>>(() =>
import('react-datepicker').then(...)
);
// In render:
<Suspense fallback={<SkeletonLoader />}>
<ReactDatePicker ... />
</Suspense>
```
On slower CI runners (GitHub Actions vs depot.dev), the lazy load takes
longer, causing tests to timeout while still showing skeletons instead
of the actual date picker content.
## Fix
Increased `findByText` timeout from the default 1000ms to 10000ms for
tests that wait for the date picker to load:
- `DateTimeFieldInput.stories.tsx` - 4 stories fixed
- `InternalDatePicker.stories.tsx` - 2 stories fixed
## Why This Wasn't Flaky Before
depot.dev runners have faster I/O and more consistent performance, so
the lazy load completed quickly. GitHub Actions runners have more
variable performance, causing the load to sometimes exceed the 1000ms
default timeout.
