feat(mobile): add local QR scanning and desktop pairing invitations

apps/mobile/src/qr.mjs

@@ -0,0 +1,50 @@
+import qrcode from './vendor/qrcode.mjs'
+
+export function drawQr(canvas, text) {
+  const qr = qrcode(0, 'M'); qr.addData(text); qr.make()
+  const count = qr.getModuleCount(), scale = 5, margin = 4
+  canvas.width = canvas.height = (count + margin * 2) * scale
+  const ctx = canvas.getContext('2d'); ctx.fillStyle = '#fff'; ctx.fillRect(0, 0, canvas.width, canvas.height)
+  ctx.fillStyle = '#000'
+  for (let y = 0; y < count; y++) for (let x = 0; x < count; x++)
+    if (qr.isDark(y, x)) ctx.fillRect((x + margin) * scale, (y + margin) * scale, scale, scale)
+}
+
+export class InviteScanner {
+  constructor(video, onCode) { this.video = video; this.onCode = onCode; this.epoch = 0; this.canvas = document.createElement('canvas') }
+  decode(source, width, height) {
+    if (!width || !height) return null
+    const scale = Math.min(1, 1280 / Math.max(width, height))
+    this.canvas.width = Math.round(width * scale); this.canvas.height = Math.round(height * scale)
+    const ctx = this.canvas.getContext('2d', { willReadFrequently: true })
+    ctx.drawImage(source, 0, 0, this.canvas.width, this.canvas.height)
+    const pixels = ctx.getImageData(0, 0, this.canvas.width, this.canvas.height)
+    return globalThis.jsQR(pixels.data, pixels.width, pixels.height)?.data
+  }
+  async image(file) {
+    this.stop(); const epoch = this.epoch
+    if (!file || file.size > 8 * 1024 * 1024) throw new Error('QR resmi en fazla 8 MB olabilir.')
+    const bitmap = await createImageBitmap(file)
+    let result
+    try { result = this.decode(bitmap, bitmap.width, bitmap.height) } finally { bitmap.close() }
+    if (epoch !== this.epoch) return
+    if (!result) throw new Error('Resimde QR okunamadı; daha net bir görüntü deneyin.')
+    await this.onCode(result)
+  }
+  async start() {
+    this.stop(); const epoch = this.epoch
+    const stream = await navigator.mediaDevices.getUserMedia({ video: { facingMode: 'environment' }, audio: false })
+    if (epoch !== this.epoch) { stream.getTracks().forEach(t => t.stop()); return }
+    this.stream = stream; this.video.srcObject = stream; this.video.hidden = false
+    try {
+      await this.video.play()
+      if (epoch !== this.epoch) return
+      this.timer = setInterval(() => {
+        const result = this.decode(this.video, this.video.videoWidth, this.video.videoHeight)
+        if (result) { this.stop(); void this.onCode(result).catch(error => this.onError?.(error)) }
+      }, 250)
+      this.limit = setTimeout(() => this.stop(), 60000)
+    } catch (error) { this.stop(); throw error }
+  }
+  stop() { this.epoch++; clearInterval(this.timer); clearTimeout(this.limit); this.stream?.getTracks().forEach(t => t.stop()); this.stream = null; this.video.srcObject = null; this.video.hidden = true }
+}