cdrom: fix cuesheet parsing for mixed-mode CDs

The first track of the cuesheet was skip from the parser.

We set a track type other than audio, so it's skipped by TOC_GetAudioRange().

Fix the CDDA ReadDir() when a track index offset is needed. After TOC_GetAudioRange(), i_cdda_tracks represents the number of real tracks. The first index is i_cdda_first.

Fixes #26036 (closed)