Mask broken fibers. #451
Description
Misha Rashkovetskyi noticed that Nightwatch is plotting calibrated spectra from broken fibers, resulting in over-subtraction of skylines and creating large negative fluxes. See the example for fiber 3914 in petal 7 discussed on 2024-12-27. Damaged fibers are indicated in the DESI_SPECTRO_CALIB yaml files, so Nightwatch should mask these out.