fix(android): pairing QR now actually scannable

Camera decode failed because every lever was at its minimum: the web
modal generated the QR at 112px (~2.5px per module before upscaling),
the analysis stream was CameraX's 640x480 default, and ZXing ran
without TRY_HARDER. Generate the QR at 512px (displayed 192px with a
real quiet zone), analyze at 1280x720, decode with TRY_HARDER plus an
inverted-luminance fallback. v0.4.14 (versionCode 18).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/components/CompanionIntroOverlay.vue

@@ -93,7 +93,9 @@
               </div>
 
               <div class="flex justify-center mb-4">
-                <div class="w-[128px] rounded-2xl border border-white/10 bg-white/[0.03] p-1 overflow-hidden">
+                <!-- Bigger than the download QR: this one is scanned by the
+                     companion app camera, and physical size drives decode. -->
+                <div class="w-[192px] rounded-2xl border border-white/10 bg-white/[0.03] p-1 overflow-hidden">
                   <img
                     v-if="pairQrDataUrl"
                     :src="pairQrDataUrl"
@@ -218,9 +220,12 @@ watch(companionIntroRequested, (requested) => {
 
 watch(visible, async (isVisible) => {
   if (!isVisible) return
+  // Generate large and let CSS scale down — at 112px source a ~45-module QR
+  // is 2.5px/module, which camera decoders (the companion app included)
+  // routinely fail on. 512px keeps every module crisp.
   qrDataUrl.value = await QRCode.toDataURL(companionDownloadUrl, {
-    width: 112,
-    margin: 1,
+    width: 512,
+    margin: 2,
     errorCorrectionLevel: 'M',
     color: {
       dark: '#111111',
@@ -261,9 +266,11 @@ async function showPairScreen() {
   step.value = 'pair'
   if (!pairQrDataUrl.value) {
     pairingUrl.value = await buildPairingUrl()
+    // Large source + a real quiet zone; this QR is scanned by the companion
+    // app's camera, so give it every advantage (see download QR note above).
     pairQrDataUrl.value = await QRCode.toDataURL(pairingUrl.value, {
-      width: 112,
-      margin: 1,
+      width: 512,
+      margin: 3,
       errorCorrectionLevel: 'M',
       color: {
         dark: '#111111',