Fix Docker build by excluding test files and using explicit project path

Dockerfile

@@ -9,8 +9,8 @@ WORKDIR /src
 COPY . .
 
 # Restore & publish (self-contained trimming can be added later if desired)
-RUN dotnet restore
-RUN dotnet publish -c $BUILD_CONFIGURATION -o /app/publish --no-restore
+RUN dotnet restore SimpleIdp.csproj
+RUN dotnet publish SimpleIdp.csproj -c $BUILD_CONFIGURATION -o /app/publish --no-restore
 
 # =========================
 # Runtime stage

SimpleIdp.csproj

@@ -4,6 +4,11 @@
 		<OutputType>Exe</OutputType>
 		<ErrorOnDuplicatePublishOutputFiles>false</ErrorOnDuplicatePublishOutputFiles>
 	</PropertyGroup>
+	<ItemGroup>
+		<Compile Remove="SimpleIdp.Tests/**" />
+		<EmbeddedResource Remove="SimpleIdp.Tests/**" />
+		<None Remove="SimpleIdp.Tests/**" />
+	</ItemGroup>
 	<ItemGroup>
 		<PackageReference Include="Microsoft.AspNetCore.Authentication" Version="2.3.0" />
 		<PackageReference Include="SimpleIdServer.IdServer.Pwd" Version="6.0.*-*" />