feat(11-04): add UpdateProfileAsync to ProfileService and ImportLogoFromBytesAsync to BrandingService

- ProfileService.UpdateProfileAsync: replaces profile by name and persists the change
- IBrandingService: add ImportLogoFromBytesAsync to interface contract
- BrandingService.ImportLogoFromBytesAsync: validates magic bytes, compresses if > 512KB, returns LogoData
- BrandingService.ImportLogoAsync: refactored to delegate to ImportLogoFromBytesAsync
- ProfileServiceTests: 2 new tests (UpdateProfileAsync happy path + KeyNotFoundException)
- BrandingServiceTests: 2 new tests (ImportLogoFromBytesAsync valid PNG + invalid bytes)
- Tests.csproj: suppress NU1701 for pre-existing LiveCharts2/OpenTK transitive warnings

SharepointToolbox.Tests/Services/BrandingServiceTests.cs

@@ -220,4 +220,25 @@ public class BrandingServiceTests : IDisposable
 
         Assert.Null(result);
     }
+
+    [Fact]
+    public async Task ImportLogoFromBytesAsync_ValidPngBytes_ReturnsPngLogoData()
+    {
+        var service = CreateService();
+        var pngBytes = MinimalPngBytes();
+
+        var result = await service.ImportLogoFromBytesAsync(pngBytes);
+
+        Assert.Equal("image/png", result.MimeType);
+        Assert.Equal(Convert.ToBase64String(pngBytes), result.Base64);
+    }
+
+    [Fact]
+    public async Task ImportLogoFromBytesAsync_InvalidBytes_ThrowsInvalidDataException()
+    {
+        var service = CreateService();
+        var invalidBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05 };
+
+        await Assert.ThrowsAsync<InvalidDataException>(() => service.ImportLogoFromBytesAsync(invalidBytes));
+    }
 }