## Summary
After upgrading to Qt 6.12.0, `Super + Space` opens the Omarchy menu as a fully black screen. The shell's `Color` singleton sub-objects (`Color.menu`, `Color.tooltip`, `Color.bar`, ...) evaluate to `undefined`, so every themed surface (menu, tooltips, OSD, buttons) gets no colors.

## System
- Omarchy 4.0.4-1, Hyprland 0.56.2, kernel 7.2.8-5-omarchy-bore
- Lenovo YOGA 510-14ISK, Intel i7-6500U (Skylake iGPU), 1366x768
- Upgraded the same day: qt6-base 6.11.2-3 -> 6.12.0-2, qt6-declarative 6.11.2-2 -> 6.12.0-1, qt6-wayland -> 6.12.0-1, quickshell 0.3.1-1 -> 0.3.2-1
- Theme: sunset (custom theme under ~/.config/omarchy/themes)

## Steps to reproduce
1. Update to qt6 6.12.0 + quickshell 0.3.2.
2. Press Super + Space (or run `omarchy-menu toggle`).
3. `hyprctl layers` shows the `omarchy-menu` layer at full size, but the screen is black.

## Log (`qs log -p /usr/share/omarchy/shell`)
```
@plugins/bar/Bar.qml[75:3]: Unable to assign [undefined] to QColor
@Ui/PanelToolTip.qml[22:-1]: TypeError: Cannot read property 'background' of undefined
plugins/menu/Menu.qml[87:-1]: TypeError: Cannot read property 'background' of undefined
plugins/menu/Menu.qml[91:-1]: TypeError: Cannot read property 'scrim' of undefined
@Commons/Border.qml[25:-1]: TypeError: Cannot read property 'menu.border-alpha' of undefined
```
Errors are present from shell startup (before the menu is opened), and affect the bar, OSD, reminders, and Ui/* controls too.

## Ruled out
- `~/.config/omarchy/shell.toml` override (removed it: same errors)
- QML disk cache (`~/.cache/quickshell/qmlcache` removed: same errors)
- `omarchy restart shell`
- `pacman -Qkk omarchy`: no modified files; theme `colors.toml` and `shell.toml` in `~/.local/state/omarchy/current/theme` are valid

## Suspected cause
Behavior change in Qt 6.12 around `pragma Singleton` / `readonly property QtObject` in `shell/Commons/Color.qml`. Not confirmed; I did not downgrade Qt.

Full `omarchy debug` output available on request.