Add QR code scanning functionality with new QRScanner component

- Introduced a new QRScanner component to facilitate QR code scanning within the application.
- Integrated QR code scanning capabilities into the SendDialog.vue, allowing users to scan QR codes for payment destinations.
- Updated package.json and package-lock.json to include the qr-scanner library for QR code processing.
- Enhanced user experience by providing visual feedback and error handling during the scanning process.

These changes improve the payment workflow by enabling users to easily scan QR codes for transactions.

src/components/ui/qr-scanner.vue

@@ -0,0 +1,134 @@
+<template>
+  <div class="relative">
+    <!-- Camera Permission Request -->
+    <div v-if="hasPermission === false" class="text-center p-6 space-y-4">
+      <div class="text-destructive">
+        <svg class="w-12 h-12 mx-auto mb-2" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+          <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M15 10l4.553-2.276A1 1 0 0121 8.618v6.764a1 1 0 01-1.447.894L15 14M5 18h8a2 2 0 002-2V8a2 2 0 00-2-2H5a2 2 0 00-2 2v8a2 2 0 002 2z"></path>
+        </svg>
+      </div>
+      <div>
+        <h3 class="font-medium text-lg">Camera Access Required</h3>
+        <p class="text-sm text-muted-foreground mt-1">{{ error || 'Please allow camera access to scan QR codes' }}</p>
+      </div>
+      <Button @click="requestPermission" variant="outline">
+        Try Again
+      </Button>
+    </div>
+
+    <!-- Scanner Interface -->
+    <div v-else class="space-y-4">
+      <!-- Video Element -->
+      <div class="relative bg-black rounded-lg overflow-hidden">
+        <video
+          ref="videoEl"
+          class="w-full h-64 sm:h-80 object-cover"
+          muted
+          playsinline
+        ></video>
+
+        <!-- Overlay with scanning indicator -->
+        <div v-if="isScanning" class="absolute inset-0 pointer-events-none">
+          <!-- Scanning frame -->
+          <div class="absolute inset-4 border-2 border-white rounded-lg">
+            <div class="absolute top-0 left-0 w-6 h-6 border-t-4 border-l-4 border-primary rounded-tl-lg"></div>
+            <div class="absolute top-0 right-0 w-6 h-6 border-t-4 border-r-4 border-primary rounded-tr-lg"></div>
+            <div class="absolute bottom-0 left-0 w-6 h-6 border-b-4 border-l-4 border-primary rounded-bl-lg"></div>
+            <div class="absolute bottom-0 right-0 w-6 h-6 border-b-4 border-r-4 border-primary rounded-br-lg"></div>
+          </div>
+
+          <!-- Scanning line animation -->
+          <div class="absolute inset-x-4 top-4 bottom-4 overflow-hidden">
+            <div class="h-0.5 bg-primary/70 animate-pulse"></div>
+          </div>
+        </div>
+
+        <!-- Loading state -->
+        <div v-if="!isScanning && hasPermission !== false" class="absolute inset-0 flex items-center justify-center bg-black/50">
+          <div class="text-center text-white">
+            <Loader2 class="w-8 h-8 animate-spin mx-auto mb-2" />
+            <p class="text-sm">Starting camera...</p>
+          </div>
+        </div>
+      </div>
+
+      <!-- Controls -->
+      <div class="flex items-center justify-between">
+        <div class="text-sm text-muted-foreground">
+          {{ isScanning ? 'Point camera at QR code' : 'Preparing scanner...' }}
+        </div>
+
+        <div class="flex gap-2">
+          <!-- Flash toggle (if available) -->
+          <Button
+            v-if="flashAvailable"
+            @click="toggleFlash"
+            variant="outline"
+            size="sm"
+          >
+            <svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M13 10V3L4 14h7v7l9-11h-7z"></path>
+            </svg>
+          </Button>
+
+          <!-- Close scanner -->
+          <Button @click="$emit('close')" variant="outline" size="sm">
+            Close
+          </Button>
+        </div>
+      </div>
+
+      <!-- Error display -->
+      <div v-if="error" class="text-destructive text-sm p-3 bg-destructive/10 rounded-md">
+        {{ error }}
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, onMounted, onUnmounted, nextTick } from 'vue'
+import { Button } from '@/components/ui/button'
+import { Loader2 } from 'lucide-vue-next'
+import { useQRScanner } from '@/composables/useQRScanner'
+
+interface Emits {
+  (e: 'result', value: string): void
+  (e: 'close'): void
+}
+
+const emit = defineEmits<Emits>()
+
+const videoEl = ref<HTMLVideoElement>()
+const flashAvailable = ref(false)
+
+const {
+  isScanning,
+  hasPermission,
+  error,
+  startScanning,
+  stopScanning,
+  toggleFlash,
+  hasFlash
+} = useQRScanner()
+
+const requestPermission = async () => {
+  if (videoEl.value) {
+    await startScanning(videoEl.value, (result) => {
+      emit('result', result)
+    })
+    flashAvailable.value = await hasFlash()
+  }
+}
+
+onMounted(async () => {
+  await nextTick()
+  if (videoEl.value) {
+    await requestPermission()
+  }
+})
+
+onUnmounted(() => {
+  stopScanning()
+})
+</script>