atlas: add une (U) NIR line list, drop corrupt une.fits

6900 Uranium lines, vacuum Angstrom (5001-14398), from Sarmiento et al.
Remove une.fits: only the first 2.8% of rows held valid data (14539-14591 A,
past the line list anyway); the rest was uninitialized garbage. The atlas
synthesizes a reference spectrum from the list, so the fits isn't needed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ivh