The save was broken in two ways:
1. Only current_track + upcoming (capped at 20) were saved, dropping
all history tracks. Queue was reconstructed incomplete on restore.
2. Track metadata (hires, bit_depth, sample_rate, source, etc.) was
not being persisted, only the basic 6 fields.
Add v2_get_all_queue_tracks command that returns the full uncapped
track list with correct current_index. Use it in saveSessionBeforeClose
instead of the capped v2_get_queue_state. Map all metadata fields.