diskOS Disco! 1.2.3

Larger Modes controls and fixes for Immersive transitions, app shortcuts, editor
cancellation and file operations. Album Roulette remains a separate user app at
version 1.3.1. The underlying diskOS version remains 1.2.4.

• Modes uses 56px rows and 22px labels, with the bottom button fitting closer to the rim.
• Disco Immersive keeps its cover opaque during the return to Music, preventing the
  shared Ring layout from flashing through. No-track entry stays on the current screen,
  and rapid reopening cancels stale close callbacks.
• Music Assistant server and weather location settings survive cancellation. Saving
  an empty server field still deliberately selects Auto.
• App shortcuts identify installed apps by directory, supporting duplicate and long
  display names. Unique legacy shortcuts remain compatible; ambiguous ones need reassignment.
• Copies preserve pre-existing .part files. Replacement copies finish staging before
  modifying the original destination, restore it on failed installation, and retain the
  backup if restoration fails. Replacement moves need room for a staged copy.
• Playing replacement destinations, including folders, are protected in the picker
  and worker. Source playback protection is rechecked before worker operations.
• Signed SD update documentation now covers existing keys, signing, verification,
  trial acceptance, rollback and diagnostics.

Validation: 44 actual-LVGL scenarios and focused filesystem, shortcut, configuration
and playback-state tests passed. Production MIPS build, MIPS32r2/FP64/NaN2008 ABI,
embedded version, theme/punctuation gates and signed-update verification passed.
Physical-device verification remains necessary.

Install the updated mq_ui using your existing owner keys and the signed SD workflow
in UPDATING.md. A UI update does not reinstall Album Roulette.
This local candidate has not been committed, tagged or published.