fix(dialog): remove KWin blur from DialogWindow to fix dark theme issue

DialogWindow previously enabled KWin blur (enableBlurWindow: true)
unconditionally. When an application forces dark theme (e.g.,
dde-launchpad in fullscreen mode), the blur shows the dark background
through the dialog, making it appear dark even in light system theme.

Remove enableBlurWindow and set color to transparent directly, so
DialogWindow uses the standard DTK palette without KWin blur side
effects.

Bug: https://pms.uniontech.com/bug-view-359629.html

Author: robertkill

qt6/src/qml/DialogWindow.qml

@@ -19,10 +19,9 @@ Window {
     D.DWindow.enableSystemResize: false
     D.DWindow.motifFunctions: D.WindowManagerHelper.FUNC_ALL & ~D.WindowManagerHelper.FUNC_RESIZE
     D.DWindow.wmWindowTypes: D.WindowManagerHelper.DialogType
-    D.DWindow.enableBlurWindow: true
     flags: Qt.Dialog | Qt.WindowCloseButtonHint | Qt.MSWindowsFixedSizeDialogHint
     D.ColorSelector.family: D.Palette.CrystalColor
-    color: D.DWindow.enableBlurWindow ? "transparent" : (active ? D.DTK.palette.window : D.DTK.inactivePalette.window)
+    color: "transparent"
     height: content.height
     width: content.width