Phase-2 Slice 12a. Per the user's decision (DQ3), the "My QBZ" rename/change-icon
lives in Settings > Appearance, not a sidebar context menu:
- src/myqbz_prefs.rs: per-user {label, icon_path} persisted to
users/<id>/myqbz_branding.json (scoped like plex_settings/tray_settings);
init_for_user/seed/set_label/pick_icon(rfd)/reset_icon. Blank label coerces to
"My QBZ"; a missing/deleted custom icon falls back to the default my-qbz.svg
without crashing (path preserved). 4 unit tests.
- ui/settings/AppearanceSettings.slint: a "My QBZ" SettingRow (icon preview +
label LineEdit + Change icon... + Reset).
- ui/shell/Sidebar.slint: the My QBZ row binds label/icon to MyQbzBrandingState
(raw-icon flag renders a custom user image untinted; default glyph stays tinted).
- Seeded on enter_shell.
Backend crates untouched. cargo check -p qbz-slint green.
cc