Add support for sending using a QR code

closes #196

ShareExtension/QrCodeBackgroundView.swift

@@ -0,0 +1,46 @@
+//
+//  QrCodeBackgroundView.swift
+//  ShareExtension
+//
+//  Created by Grishka on 07.08.2025.
+//
+
+import Foundation
+import Metal
+import MetalKit
+
+class QrCodeBackgroundView:MTKView{
+	private var commandQueue:MTLCommandQueue?
+	private var commandBuffer:MTLCommandBuffer?
+	
+	override func awakeFromNib() {
+		super.awakeFromNib()
+		isPaused=true
+		enableSetNeedsDisplay=false
+		device=MTLCreateSystemDefaultDevice()
+		let brightness=1.5
+		clearColor=MTLClearColor(red: brightness, green: brightness, blue: brightness, alpha: 1)
+		
+		let mtlLayer:CAMetalLayer=(layer as? CAMetalLayer)!
+		mtlLayer.wantsExtendedDynamicRangeContent=true
+		mtlLayer.cornerRadius=20
+		mtlLayer.masksToBounds=true
+		colorspace=CGColorSpace(name: CGColorSpace.extendedSRGB)
+		colorPixelFormat = .rgba16Float
+		
+		commandQueue=device!.makeCommandQueue()
+		commandBuffer=commandQueue!.makeCommandBuffer()
+		draw()
+	}
+	
+	override func draw(_ dirtyRect: NSRect) {
+		guard let commandBuffer=commandBuffer else {return}
+		if let descriptor=currentRenderPassDescriptor, let encoder=commandBuffer.makeRenderCommandEncoder(descriptor: descriptor){
+			encoder.endEncoding()
+			if let currentDrawable=currentDrawable{
+				commandBuffer.present(currentDrawable)
+			}
+		}
+		commandBuffer.commit()
+	}
+}