32991301dd
- default_theme_id() returns "dark" (was briefly "classic" after the
rename commit 20b7a61)
- sanitized() migrates "default" and "classic" → "dark" so existing
settings.json files are upgraded automatically on next launch
- Registry lists Dark first so the Settings picker opens with it at top
- Classic remains available as an option in the picker
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>