test(bff): /health returns 200 Healthy (refs #28)

Add the BFF Api/Tests skeleton (.NET 10, ASP.NET Core minimal API, xUnit
+ WebApplicationFactory) and a failing test asserting GET /health returns
200 with a Healthy body. The endpoint does not exist yet — the test fails
with NotFound, establishing red before the implementation.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/bff/Bff.Api/Bff.Api.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

services/bff/Bff.Api/Program.cs

@@ -0,0 +1,9 @@
+var builder = WebApplication.CreateBuilder(args);
+var app = builder.Build();
+
+app.MapGet("/", () => "BFF placeholder");
+
+app.Run();
+
+// Exposed so the test host (WebApplicationFactory<Program>) can boot the app.
+public partial class Program;

services/bff/Bff.Tests/Bff.Tests.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.8" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Bff.Api\Bff.Api.csproj" />
+  </ItemGroup>
+
+</Project>

services/bff/Bff.Tests/HealthEndpointTests.cs

@@ -0,0 +1,20 @@
+using System.Net;
+using Microsoft.AspNetCore.Mvc.Testing;
+
+namespace Bff.Tests;
+
+public class HealthEndpointTests(WebApplicationFactory<Program> factory)
+    : IClassFixture<WebApplicationFactory<Program>>
+{
+    [Fact]
+    public async Task Health_endpoint_returns_200_and_reports_healthy()
+    {
+        var client = factory.CreateClient();
+
+        var response = await client.GetAsync("/health");
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var body = await response.Content.ReadAsStringAsync();
+        Assert.Contains("Healthy", body);
+    }
+}

services/bff/Bff.slnx

@@ -0,0 +1,4 @@
+<Solution>
+  <Project Path="Bff.Api/Bff.Api.csproj" />
+  <Project Path="Bff.Tests/Bff.Tests.csproj" />
+</Solution>