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/P2pQrPayloadCodecTests.cs

@@ -0,0 +1,57 @@
+using System;
+using Paca.Mobile.Core;
+using Xunit;
+
+namespace Paca.Tests.Mobile;
+
+public class P2pQrPayloadCodecTests
+{
+    [Fact]
+    public void Encode_And_Decode_Roundtrip_Succeeds()
+    {
+        var original = new P2pQrPayload
+        {
+            Host = "192.168.1.100",
+            Port = 5000,
+            Token = "secret-token-abcdef123456",
+            DeviceName = "Encep Desktop PC",
+            Fingerprint = "fp_9876543210"
+        };
+
+        string encoded = P2pQrPayloadCodec.Encode(original);
+        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);
+        Assert.Equal(original.Fingerprint, decoded.Fingerprint);
+    }
+
+    [Fact]
+    public void Decode_Invalid_Checksum_Throws()
+    {
+        var original = new P2pQrPayload
+        {
+            Host = "192.168.1.100",
+            Port = 5000,
+            Token = "secret-token",
+            DeviceName = "PC",
+            Fingerprint = "fp"
+        };
+
+        string encoded = P2pQrPayloadCodec.Encode(original);
+        // 체크섬 위조
+        string tampered = encoded.Replace("sig=", "sig=tampered");
+
+        Assert.Throws<InvalidOperationException>(() => P2pQrPayloadCodec.Decode(tampered));
+    }
+
+    [Fact]
+    public void Decode_NonPacaScheme_Throws()
+    {
+        Assert.Throws<ArgumentException>(() => P2pQrPayloadCodec.Decode("https://google.com"));
+    }
+}