### System details
Apple M1 Pro (aarch64) [also reproduces across x86_64 systems], Omarchy 4.0.2-2, Hyprland 0.56.2, Quickshell 0.3.2-1, Qt 6.12.0 (`qt6-declarative 6.12.0-1`, `qt6-base 6.12.0-2`).

### What's wrong?
Following the Qt 6.12.0 upgrade, triggering any menu or launcher overlay (`Super+Space`, `Super+Alt+Space`, `omarchy-menu toggle`) renders a 100% solid pitch black screen across the entire monitor. No menu card, rows, or text appear.

In addition, UI components across the shell log widespread runtime TypeErrors during property evaluation:
```
WARN scene: @Ui/Button.qml: TypeError: Cannot read property 'border' of undefined
WARN scene: @Ui/Button.qml: TypeError: Cannot read property 'background' of undefined
WARN scene: @Ui/PanelToolTip.qml: TypeError: Cannot read property 'border' of undefined
WARN scene: @Ui/PanelToolTip.qml: TypeError: Cannot read property 'background' of undefined
WARN scene: @Ui/PopupCard.qml: TypeError: Cannot read property 'background' of undefined
WARN scene: @Ui/TextField.qml: Unable to assign [undefined] to QColor
```

### Root Cause Analysis
In **Qt 6.12**, `QtQuick` introduced a new built-in QML singleton named `Color` (backed by the C++ class `QQuickColor`).

In Omarchy Shell (`/usr/share/omarchy/shell/`), the central theme palette singleton is declared in `Commons/qmldir` as:
```qml
singleton Color 1.0 Color.qml
```
Virtually all QML files import both:
```qml
import QtQuick
import qs.Commons
```
Because `QtQuick` now exports `Color`, it **shadows** `qs.Commons.Color`.

We verified this inside a minimal Quickshell test harness running under Qt 6.12:
```qml
import QtQuick
import Quickshell
import qs.Commons as Commons
import qs.Commons

// Evaluating identifiers:
console.log("Bare Color:", Color)          // -> QQuickColor(...) [QtQuick built-in]
console.log("Color.menu:", Color.menu)      // -> undefined
console.log("Commons.Color:", Commons.Color)// -> Color_QMLTYPE(...) [Omarchy singleton]
console.log("Commons.Color.menu.scrim:", Commons.Color.menu.scrim) // -> #80101315
```

When `Menu.qml` evaluates:
```qml
property color scrim: Color.menu.scrim
property color background: Color.menu.background
property color border: Color.menu.border
```
1. `Color.menu` resolves to `undefined` on `QQuickColor`.
2. `root.scrim` receives `undefined`, which QML coerces to `#000000` (100% opaque black).
3. The fullscreen scrim `Rectangle { anchors.fill: parent; color: root.scrim }` renders as an opaque solid black sheet covering the screen.
4. The `BorderSurface` card fails with `TypeError: Cannot read property 'border' of undefined` and fails to render.

This root cause directly explains both **#15071** ("Super+Space launcher overlay renders 100% black") and **#15085** ("Bar renders solid black with no text when bar.transparent=false / Color.bar undefined").

### Steps to Reproduce
1. Upgrade to Qt 6.12 (`pacman -Syu` with `qt6-declarative 6.12.0-1`).
2. Trigger the menu: `omarchy-menu toggle` or `Super+Space`.
3. The entire monitor turns solid black until the menu is closed.