server.py cannot load due to a ComfyUI internal module shadowing bug
(comfy/utils.py file shadows utils/ package). Decouple init_extra_nodes()
from server.py loading so NODE_CLASS_MAPPINGS still gets populated from
comfy_extras (UpscaleModelLoader, etc.) even without full PromptServer setup.
Also fix app.py to re-read from cached sys.modules[nodes] after
import_custom_nodes() instead of using stale initial copy.
Fixes the upscale-model-loader runtime e2e test.
Move generated torch imports until after add_extra_model_paths runs so exported scripts do not trigger ComfyUI's early-torch warning during startup. Update export assertions and checked-in runtime generated fixtures to match the new main() ordering.
Peyton DeNiro