Fix mastering item support and Track Organizer sorting

[lsooxlla8]

Summary

• support audio, MIDI, generated-source, and empty selected items in Prepare Selected Items for Mastering
• prevent Track Organizer from crashing on automatic numbered folders without configured order paths
• keep full Organizer diagnostics in the console while showing a concise rollback dialog
• combine Freeze Toggle and Smart Freeze Toggle into one README entry

Validation

• Lua parsing for all changed scripts and tests
• mixed-item mastering mock
• Track Organizer first-run and rerun mocks with automatic OTHER families
• git diff --check
• xmllint index.xml