feat(ads/seo/release): v1.2.0 with live Google Ads, isolated ad profile, ads.txt, and SEO/AEO/GEO optimization

tests/Paca.Tests/Mobile/MobileQrPairingUiGateTests.cs

@@ -0,0 +1,55 @@
+using System.IO;
+using Paca.Mobile.Core;
+using Xunit;
+
+namespace Paca.Tests.Mobile;
+
+public class MobileQrPairingUiGateTests
+{
+    private static readonly string SolutionRoot = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", ".."));
+
+    [Fact]
+    public void Gate_QrPayloadCodec_Roundtrip_EnsuresIntegrity()
+    {
+        var original = new P2pQrPayload
+        {
+            Host = "192.168.1.100",
+            Port = 52100,
+            Token = "secret-token-xyz-12345",
+            DeviceName = "MyDesktop-PC",
+            Fingerprint = "fp-abc"
+        };
+
+        var encoded = P2pQrPayloadCodec.Encode(original);
+        Assert.NotNull(encoded);
+        Assert.StartsWith("paca://pair?", encoded);
+
+        var decoded = P2pQrPayloadCodec.Decode(encoded);
+        Assert.NotNull(decoded);
+        Assert.Equal(original.Host, decoded.Host);
+        Assert.Equal(original.Port, decoded.Port);
+        Assert.Equal(original.Token, decoded.Token);
+        Assert.Equal(original.DeviceName, decoded.DeviceName);
+    }
+
+    [Fact]
+    public void Gate_QrPayloadCodec_RejectsCorruptOrInvalidQr()
+    {
+        Assert.Throws<ArgumentException>(() => P2pQrPayloadCodec.Decode(""));
+        Assert.Throws<ArgumentException>(() => P2pQrPayloadCodec.Decode("INVALID_QR_FORMAT"));
+        Assert.Throws<InvalidOperationException>(() => P2pQrPayloadCodec.Decode("paca://pair?h=127.0.0.1&p=5000&t=tok&sig=wrong"));
+    }
+
+    [Fact]
+    public void Gate_SyncSettingsPage_Contains_QrScanButton_And_CodecWiring()
+    {
+        var syncPagePath = Path.Combine(SolutionRoot, "src", "Paca.Mobile", "SyncSettingsPage.cs");
+        Assert.True(File.Exists(syncPagePath), $"SyncSettingsPage.cs not found at {syncPagePath}");
+
+        var code = File.ReadAllText(syncPagePath);
+        Assert.True(code.Contains("P2pQrPayloadCodec.Decode") || code.Contains("P2pQrPayloadCodec"),
+            "SyncSettingsPage.cs must wire P2pQrPayloadCodec to decode QR scan results");
+        Assert.True(code.Contains("QR") || code.Contains("Qr"),
+            "SyncSettingsPage.cs must provide a QR Scan pairing interaction element");
+    }
+}