Fix touch app console bleed-through on linuxfb backend

Add explicit background color to ApplicationWindow to prevent the Linux
console from showing through on linuxfb. Without GPU compositing, Qt only
redraws dirty regions, leaving untouched areas transparent to the framebuffer.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

dune-weaver-touch/qml/main.qml

@@ -5,6 +5,7 @@ import QtQuick.Dialogs
 import QtQuick.VirtualKeyboard 2.15
 import DuneWeaver 1.0
 import "components"
+import "components" as Components
 
 ApplicationWindow {
     id: window
@@ -13,6 +14,11 @@ ApplicationWindow {
     height: 480
     title: "Dune Weaver Touch"
 
+    // Solid background to prevent console bleed-through on linuxfb
+    // linuxfb doesn't have proper compositing, so we need to ensure
+    // the entire window is filled with an opaque color
+    color: Components.ThemeManager.backgroundColor
+
     property int currentPageIndex: 0
     property alias stackView: stackView
     property alias backend: backend