## Summary
Removes the `CategoryTree` Pennant feature flag so the parent/child
category tree UI is active for all existing and new users.
## Changes
- Delete `app/Features/CategoryTree.php` (flag resolved `false`).
- `CategoryController` — drop `Feature`/`CategoryTreeFeature` imports
and the `categoryTreeEnabled` Inertia prop.
- `parent-category-field.tsx` — remove the `usePage` flag read and `if
(!enabled) return null` gate; the parent field now always renders.
## Testing
- `vendor/bin/pint --dirty` — pass
- `bun run lint` — clean (1 pre-existing unrelated warning in
`chart.tsx`)
- `php artisan test tests/Feature/Settings/CategoryTreeTest.php` — 11
passed
- `php artisan test tests/Feature/Settings/CategoryTest.php` — 32 passed
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