Dark theme sin graph

This example is the same as Basic sin graph, except that the theme has been extensively customised. Changes include:

• Dark background and light axes
• Light text, with adjusted font weights and styles
• Light legend

 // SPDX-FileCopyrightText: Copyright (c) 2024 Refeyn Ltd and other QuickGraphLib contributors
 // SPDX-License-Identifier: MIT

 import QtQuick
 import QuickGraphLib as QuickGraphLib
 import QuickGraphLib.GraphItems as QGLGraphItems
 import QuickGraphLib.PreFabs as QGLPreFabs

 QGLPreFabs.XYAxes {
     id: axes

     background.color: "black"
     grid.strokeColor: "#33ffffff"
     viewRect: Qt.rect(-20, -1.1, 760, 2.2)
     xAxis.labelColor: "#ffaaaa"
     xAxis.labelFont.bold: true
     xAxis.strokeColor: "white"
     xAxis.tickLabelColor: "white"
     xAxis.tickLabelFont.italic: true
     xLabel: "Angle (°)"
     yAxis.labelColor: "#ffaaaa"
     yAxis.labelFont.bold: true
     yAxis.strokeColor: "white"
     yAxis.tickLabelColor: "white"
     yAxis.tickLabelFont.italic: true
     yLabel: "Value"

     QGLGraphItems.Line {
         id: sinLine

         dataTransform: axes.dataTransform
         path: QuickGraphLib.Helpers.linspace(0, 720, 100).map(x => Qt.point(x, Math.sin(x / 180 * Math.PI)))
         strokeColor: "red"
         strokeWidth: 2
     }
     QGLGraphItems.BasicLegend {
         anchors.margins: 10
         anchors.right: parent.right
         anchors.top: parent.top
         border.color: "white"
         color: "#33ffffff"

         QGLGraphItems.BasicLegendItem {
             strokeColor: sinLine.strokeColor
             text: "Sin(θ)"
             textColor: "white"
         }
     }
 }