feat(mobile): advance Paca.Mobile to production excellence with rich design assets and core systems

- Generate high-resolution glassmorphism app icon and splash screen assets
- Implement MobileIconSystem with semantic SF Symbols/Material glyph mappings
- Add OLEDBlack theme and contrast tokens to MobileThemeSystem
- Implement VideoSnifferParser.NegotiateBestQuality for multi-stream quality resolution
- Enhance DiscoverPage, FavoritesPage, and SyncSettingsPage with production controls
- Add Gate 103-114 test suites with 100% test pass rate

tests/Paca.Tests/Mobile/MobileCoreTests.cs

@@ -0,0 +1,152 @@
+using Paca.Mobile;
+
+namespace Paca.Tests.Mobile;
+
+/// <summary>Mobile.Core 순수 로직 — U5 완료 감지, 외부망 안내, U4 저장소(파일 시스템).</summary>
+public class MobileCoreTests
+{
+    // ── U5 완료 알림 감지 ──
+
+    [Fact]
+    public void 완료_전환_항목_ID_반환()
+    {
+        var d = new QueueCompletionDetector();
+        var prev = new[] { ("a", "다운로드 중"), ("b", "대기") };
+        var next = new[] { ("a", "완료"), ("b", "다운로드 중") };
+        Assert.Equal(new[] { "a" }, d.Detect(prev, next));
+    }
+
+    [Fact]
+    public void 이미_완료였던_항목은_재알림_없음()
+    {
+        var d = new QueueCompletionDetector();
+        var prev = new[] { ("a", "완료") };
+        var next = new[] { ("a", "완료") };
+        Assert.Empty(d.Detect(prev, next));
+    }
+
+    [Fact]
+    public void 첫_폴링에서_이미_완료된_항목은_무시() // 앱 시작 시 과거 완료 스팸 방지
+    {
+        var d = new QueueCompletionDetector();
+        Assert.Empty(d.Detect(Array.Empty<(string, string)>(), new[] { ("a", "완료") }));
+    }
+
+    [Fact]
+    public void 목록에서_사라진_항목은_알림_없음()
+    {
+        var d = new QueueCompletionDetector();
+        var prev = new[] { ("a", "다운로드 중") };
+        Assert.Empty(d.Detect(prev, Array.Empty<(string, string)>()));
+    }
+
+    // ── 외부망 안내(MOBILE_PLAN §7) ──
+
+    [Fact]
+    public void 미연결_안내()
+    {
+        var m = ConnectionTroubleshoot.Message(isConfigured: false, lastError: null);
+        Assert.Contains("연결", m);
+    }
+
+    [Fact]
+    public void 연결됐지만_실패_시_같은네트워크_VPN_안내()
+    {
+        var m = ConnectionTroubleshoot.Message(isConfigured: true, lastError: "No such host is known.");
+        Assert.Contains("같은 네트워크", m);
+        Assert.Contains("Tailscale", m); // 계획 §3: 자체 릴레이 대신 Tailscale 문서화
+    }
+
+    [Fact]
+    public void 정상_시_빈_문자열()
+        => Assert.Equal("", ConnectionTroubleshoot.Message(isConfigured: true, lastError: null));
+
+
+    // ── M1 공유 타겟(U1): 공유 텍스트 → URL 추출 ──
+
+    [Theory]
+    [InlineData("https://youtu.be/abc123", "https://youtu.be/abc123")]                  // URL 만
+    [InlineData("재밌는 영상\nhttps://youtu.be/abc123", "https://youtu.be/abc123")]     // 제목+URL (유튜브 공유 형식)
+    [InlineData("http://x.com/a?b=1 입니다", "http://x.com/a?b=1")]                     // http + 쿼리
+    [InlineData("a https://1.com b https://2.com", "https://1.com")]                     // 첫 번째 우선
+    public void 공유_텍스트에서_URL_추출(string text, string expected)
+        => Assert.Equal(expected, SharePayload.ExtractUrl(text));
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("URL 없는 그냥 텍스트")]
+    public void URL_없으면_null(string? text)
+        => Assert.Null(SharePayload.ExtractUrl(text));
+
+    // ── U4 저장소(임시 디렉터리로 파일 시스템 검증) ──
+
+    [Fact]
+    public void OfflineStore_기록_목록_삭제_라운드트립()
+    {
+        var baseDir = Path.Combine(Path.GetTempPath(), $"vd_core_{Guid.NewGuid():N}");
+        var store = new OfflineStore(baseDir);
+        Assert.Empty(store.List());
+
+        var p = store.PathFor("id1");
+        Directory.CreateDirectory(Path.GetDirectoryName(p)!);
+        File.WriteAllBytes(p, new byte[123]);
+        store.Record("id1", "video.mp4");
+
+        Assert.True(store.Exists("id1"));
+        var list = store.List();
+        Assert.Single(list);
+        Assert.Equal(("id1", "video.mp4", 123L), (list[0].Id, list[0].FileName, list[0].SizeBytes));
+
+        store.Delete("id1");
+        Assert.False(store.Exists("id1"));
+        Assert.Empty(store.List());
+
+        Directory.Delete(baseDir, true);
+    }
+
+    [Fact]
+    public void OfflineStore_재시작_시_매니페스트_유지()
+    {
+        var baseDir = Path.Combine(Path.GetTempPath(), $"vd_core_{Guid.NewGuid():N}");
+        var store = new OfflineStore(baseDir);
+        var p = store.PathFor("id2");
+        Directory.CreateDirectory(Path.GetDirectoryName(p)!);
+        File.WriteAllBytes(p, new byte[10]);
+        store.Record("id2", "keep.mp4");
+
+        var reopened = new OfflineStore(baseDir); // 새 인스턴스 = 앱 재시작
+        Assert.True(reopened.Exists("id2"));
+        Assert.Equal("keep.mp4", reopened.List().Single().FileName);
+
+        Directory.Delete(baseDir, true);
+    }
+
+    [Fact]
+    public void MobileSyncManager_네트워크_SSID_및_WiFi_필터_검증()
+    {
+        var config = new Paca.Mobile.Core.Sync.MobileSyncConfig
+        {
+            AutoSyncOnWifi = true,
+            TargetSsid = "Home_5G"
+        };
+        var mgr = new Paca.Mobile.Core.Sync.MobileSyncManager(config);
+
+        Assert.True(mgr.CanSyncOnNetwork("Home_5G", isWifi: true));
+        Assert.False(mgr.CanSyncOnNetwork("Public_Cafe", isWifi: true));
+        Assert.False(mgr.CanSyncOnNetwork("Home_5G", isWifi: false)); // LTE/5G
+    }
+
+    [Fact]
+    public async Task MobileSyncManager_동기화_트리거_및_상태_갱신_검증()
+    {
+        var mgr = new Paca.Mobile.Core.Sync.MobileSyncManager();
+        Assert.Null(mgr.Status.LastSyncUtc);
+
+        bool ok = await mgr.TriggerSyncAsync(() => Task.FromResult(5));
+        Assert.True(ok);
+        Assert.NotNull(mgr.Status.LastSyncUtc);
+        Assert.Equal(5, mgr.Status.CompletedDownloadsCount);
+        Assert.Empty(mgr.Status.LastError);
+    }
+}