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

tests/Paca.Tests/Core/SmartDeduplicationAndCollisionGateTests.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Paca.Mobile.Core;
+using Xunit;
+
+namespace Paca.Tests.Core;
+
+/// <summary>
+/// Gate 211 ~ 214: 스마트 중복 다운로드 방지 및 파일명 충돌 해소 엔진 기계적 검증
+/// </summary>
+public class SmartDeduplicationAndCollisionGateTests
+{
+    [Fact]
+    public void Gate211_Deduplication_Identifies_Same_Video_Id()
+    {
+        var existingLibrary = new List<DeduplicationRecord>
+        {
+            new("dQw4w9WgXcQ", "Rick Astley - Never Gonna Give You Up.mp4", "/media/rick.mp4", 50_000_000)
+        };
+
+        var engine = new MediaDeduplicationEngine(existingLibrary);
+
+        // 다른 URL 형식이지만 동일한 YouTube 비디오 ID
+        var result = engine.CheckDuplicate("https://youtu.be/dQw4w9WgXcQ?si=trackingToken");
+
+        Assert.True(result.IsDuplicate);
+        Assert.Equal("Rick Astley - Never Gonna Give You Up.mp4", result.ExistingFileName);
+        Assert.True(result.CanReuseExisting);
+    }
+
+    [Fact]
+    public void Gate212_Deduplication_Allows_New_Video()
+    {
+        var existingLibrary = new List<DeduplicationRecord>
+        {
+            new("dQw4w9WgXcQ", "Rick.mp4", "/media/rick.mp4", 50_000_000)
+        };
+
+        var engine = new MediaDeduplicationEngine(existingLibrary);
+        var result = engine.CheckDuplicate("https://www.youtube.com/watch?v=newVideoId999");
+
+        Assert.False(result.IsDuplicate);
+        Assert.Null(result.ExistingFileName);
+    }
+
+    [Fact]
+    public void Gate213_CollisionResolver_Generates_Numbered_Suffix()
+    {
+        var tempDir = Path.Combine(Path.GetTempPath(), "Paca_Collision_Test_" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(tempDir);
+
+        try
+        {
+            // 원본 파일 생성
+            var originalPath = Path.Combine(tempDir, "Nature_4K.mp4");
+            File.WriteAllText(originalPath, "original");
+
+            // 1차 충돌 시 -> Nature_4K (1).mp4
+            var safePath1 = FileCollisionResolver.ResolveSafePath(tempDir, "Nature_4K.mp4");
+            Assert.Equal(Path.Combine(tempDir, "Nature_4K (1).mp4"), safePath1);
+
+            // Nature_4K (1).mp4도 생성해둠
+            File.WriteAllText(safePath1, "existing (1)");
+
+            // 2차 충돌 시 -> Nature_4K (2).mp4
+            var safePath2 = FileCollisionResolver.ResolveSafePath(tempDir, "Nature_4K.mp4");
+            Assert.Equal(Path.Combine(tempDir, "Nature_4K (2).mp4"), safePath2);
+        }
+        finally
+        {
+            if (Directory.Exists(tempDir)) Directory.Delete(tempDir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public void Gate214_CollisionResolver_Preserves_When_No_Conflict()
+    {
+        var tempDir = Path.Combine(Path.GetTempPath(), "Paca_NoCollision_" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(tempDir);
+
+        try
+        {
+            var safePath = FileCollisionResolver.ResolveSafePath(tempDir, "FreshVideo.mp4");
+            Assert.Equal(Path.Combine(tempDir, "FreshVideo.mp4"), safePath);
+        }
+        finally
+        {
+            if (Directory.Exists(tempDir)) Directory.Delete(tempDir, recursive: true);
+        }
+    }
+}