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.
Split the previous monolithic implementation into focused modules for CLI handling, workflow loading, runtime bootstrap, load ordering, planning, rendering, and file I/O. Keep the public compatibility surface intact by preserving the legacy top-level wrapper while adding as the documented entrypoint. This reduces cross-cutting coupling inside the exporter and makes the runtime/bootstrap behavior easier to evolve without carrying unrelated concerns in one file.
Peyton DeNiro