Improve the user experience within the Medial Uploader modal


### User experience questions
In the above instance, I have already uploaded a test file, shown in the thumbnail. But the uploader message is still "Choose a file, No file chosen" which leaves me wondering if the file is not _**actually**_ queued, or if it's asking me to upload a second image, or would selecting the "choose a file" button override the image I just uploaded?

A second pain point in this modal is the lack of a clear path forward from this state. The only option is the "X"in the top right corner, but it's unclear whether that will "save and close" or "delete and close" my changes. Some options I think users would expect to see include "Save" (which would also close the modal and return me to the library), "Delete Image" which would clear the selected image but not close the modal and "Close without saving"

### Tidying
- Spacing and alignment
- [Style the file uploader button. ](https://tailwindcss.com/docs/hover-focus-and-other-states#file-input-buttons)

### Notes

* Meta issue: https://github.com/BeaconCMS/beacon_live_admin/issues/89
* See https://www.figma.com/file/k8NhxbRRb8hm4fc1RQHms1/Media-Library?type=design&node-id=30-57434&mode=design as guideline
* Related to https://github.com/BeaconCMS/beacon_live_admin/issues/139

Begin by locating the Medial Uploader modal in the repository and compare its current states with the linked Figma Media Library guideline. Confirm the requested controls and behavior, including save, delete, and close-without-saving, along with spacing and file-input styling. Done means the modal clearly communicates upload state and provides an unambiguous path forward.

Written by the indexing model from the issue text.