Replace ≈ with norm-based comparison in Zygote gradient tests

Agent-Logs-Url: https://github.com/JuliaQuantumControl/QuantumControl.jl/sessions/db517dc6-313e-44f8-8f48-90f2a7f85542

Co-authored-by: goerz <112306+goerz@users.noreply.github.com>

Author: Copilot

test/test_traj_zygote.jl

@@ -32,7 +32,7 @@ end
     @test grad isa NamedTuple
     @test grad.initial_state isa Vector
     expected_grad = -Ψtgt .* conj(dot(Ψ, Ψtgt)) / N
-    @test grad.initial_state ≈ expected_grad
+    @test norm(grad.initial_state - expected_grad) < 1e-14
 
 end
 
@@ -65,7 +65,7 @@ end
         @test grad.initial_state isa Nothing
         @test grad.kwargs[:x] isa Vector
         expected_grad = -Ψtgt .* conj(dot(Ψ, Ψtgt)) / N
-        @test grad.kwargs[:x] ≈ expected_grad
+        @test norm(grad.kwargs[:x] - expected_grad) < 1e-14
     end
 
 end