feat(backend): scaffold ASP.NET Core Web API with health endpoint

backend/Program.cs

@@ -0,0 +1,27 @@
+var builder = WebApplication.CreateBuilder(args);
+
+// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
+builder.Services.AddOpenApi();
+
+builder.Services.AddControllers();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (app.Environment.IsDevelopment())
+{
+    app.MapOpenApi();
+}
+else
+{
+    app.UseHttpsRedirection();
+}
+
+app.UseDefaultFiles();
+app.UseStaticFiles();
+
+app.MapControllers();
+
+app.MapFallbackToFile("index.html");
+
+app.Run();