Rework visual of QGCDelayButton

[DonLakeFlyer]

• Double-chevron indicates delay button
• Chevrons move from left to right as you hold down

[Copilot]

Pull request overview

This PR modernizes the visual design of QGCDelayButton by replacing the gradient-based progress indicator with an animated double-chevron icon that moves from left to right as the user holds the button down.

Key Changes:

• Replaces gradient/rectangle progress indicator with a moving chevron icon for better visual feedback
• Adds new SVG resource (chevron-double-right.svg) for the progress indicator
• Updates resource registration in qgcresources.qrc

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/QmlControls/QGCDelayButton.qml	Replaces gradient-based progress visualization with QGCColoredImage showing animated chevron icon
resources/chevron-double-right.svg	New SVG icon file for double-chevron indicator
qgcresources.qrc	Registers the new chevron-double-right.svg resource

[Copilot]

[nitpick] The property _sliderIndicatorMargin is defined at the bottom of the QGCColoredImage component (line 85), after all the other properties have been set. In QML, it's more conventional and readable to declare properties at the beginning of a component block, before they are used.

Consider moving this property declaration to the top of the QGCColoredImage block (after line 71) for better readability:

QGCColoredImage {
    property real _sliderIndicatorMargin: ScreenTools.defaultFontPixelWidth * 0.5
    
    anchors.topMargin:      _sliderIndicatorMargin
    anchors.bottomMargin:   _sliderIndicatorMargin
    // ... rest of properties
}