docs: Move `Bun` to the first place in tabs on Installation page

### Feature Request On [Installation page](https://wxt.dev/guide/installation.html#bootstrap-project) sections with that tab: <img width="421" height="122" alt="Image" src="https://github.com/user-attachments/assets/374b5fab-66f7-4e7f-9fdf-982347a4f253" /> Let's move `Bun` to the very left hand side, to let it be `Default`, because we've migrated a little to that manager and we're on the way to migrate completely. Also there(CLI): <img width="580" height="98" alt="Image" src="https://github.com/user-attachments/assets/baafb628-8df7-4d5d-b590-4fadaff882fb" /> It could be on the first place, you can find it there: https://github.com/wxt-dev/wxt/blob/22d1a727528b0f40ac3d9011cf3d30f17287728d/packages/wxt/src/core/initialize.ts#L45