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));
+    }
 }

SharepointToolbox.Tests/Services/ProfileServiceTests.cs

@@ -147,6 +147,32 @@ public class ProfileServiceTests : IDisposable
         await Assert.ThrowsAsync<KeyNotFoundException>(() => service.DeleteProfileAsync("NonExistent"));
     }
 
+    [Fact]
+    public async Task UpdateProfileAsync_UpdatesExistingProfile_AndPersists()
+    {
+        var service = CreateService();
+        var profile = new TenantProfile { Name = "UpdateMe", TenantUrl = "https://update.sharepoint.com", ClientId = "cid-update" };
+        await service.AddProfileAsync(profile);
+
+        // Mutate — set a ClientLogo to simulate logo update
+        profile.ClientLogo = new SharepointToolbox.Core.Models.LogoData { Base64 = "abc==", MimeType = "image/png" };
+        await service.UpdateProfileAsync(profile);
+
+        var profiles = await service.GetProfilesAsync();
+        Assert.Single(profiles);
+        Assert.NotNull(profiles[0].ClientLogo);
+        Assert.Equal("abc==", profiles[0].ClientLogo!.Base64);
+    }
+
+    [Fact]
+    public async Task UpdateProfileAsync_ProfileNotFound_ThrowsKeyNotFoundException()
+    {
+        var service = CreateService();
+        var profile = new TenantProfile { Name = "NonExistent", TenantUrl = "https://x.sharepoint.com", ClientId = "cid" };
+
+        await Assert.ThrowsAsync<KeyNotFoundException>(() => service.UpdateProfileAsync(profile));
+    }
+
     [Fact]
     public async Task SaveAsync_JsonOutput_UsesProfilesRootKey()
     {

SharepointToolbox.Tests/SharepointToolbox.Tests.csproj

@@ -6,6 +6,8 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
+    <!-- Suppress NU1701: LiveCharts2 transitive deps lack net10.0 targets but work at runtime -->
+    <NoWarn>$(NoWarn);NU1701</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>