Tests: two checks give the same answer on every CPU

The nightly ComfyUI job is the first place these two files ran with torch on
a GitHub-hosted runner, and one runner failed both on unchanged code.

- test_memory_helpers.py imported torch four times in one process:
  patch.dict(sys.modules) forgets whatever was first imported inside it. The
  fourth import ended the process without a word. Torch is now loaded before
  any test swaps modules.
- test_stitch_classic_pins.py compared blend masks by hash. The feather's
  blur takes an exp, which CPUs round differently, so two masks moved by a
  float32 step. Masks are now compared with frozen release masks at the
  tolerance the images already have, and a new test holds that file to the
  pinned hashes.

The nightly job also prints which CPU ran it.

.github/workflows/comfyui_compat.yml

@@ -97,6 +97,8 @@ jobs:
           python -m pip install -r ComfyUI/requirements.txt
           git -C ComfyUI log -1 --format='ComfyUI %h %cd %s' --date=short
           python -m pip list 2>/dev/null | grep -i -E "^(comfyui|torch) " || true
+          # Which CPU ran it: float results can differ by a last bit between CPUs.
+          lscpu | grep -E "^Model name" || true
       - name: Everything the pack takes from ComfyUI is there
         working-directory: ComfyUI-AusBoss
         run: AUSBOSS_COMFY_ROOT="$GITHUB_WORKSPACE/ComfyUI" python tests/test_comfy_core_contract.py