fix(scipy): allow rounding differences in STFT tests

Keep STFT tests enabled with precision-appropriate tolerances for
x86-64-v3 builds. Add the override under overlays/patches/scipy and
remove the commented-out test exclusions.

overlays/test-exclusions.nix

@@ -75,16 +75,6 @@ _final: prev: {
         '';
       });
 
-      # scipy = pythonPrev.scipy.overridePythonAttrs (old: {
-      #   # x86-64-v3 FFT implementations produce rounding differences outside
-      #   # these tests' strict tolerances. We accept the numerical-precision
-      #   # risk for our workloads.
-      #   disabledTests = (old.disabledTests or [ ]) ++ [
-      #     "test_roundtrip_float32"
-      #     "test_roundtrip_scaling"
-      #   ];
-      # });
-
       sentry-sdk = pythonPrev.sentry-sdk.overridePythonAttrs (old: {
         # This test globally mocks threading.current_thread while another
         # thread is running. On Python 3.14, Thread.join can race with that