* refactor: process isolation support for node replacement API
- Move REGISTERED_NODE_REPLACEMENTS global to NodeReplaceManager instance state
- Add NodeReplacement class to ComfyAPI_latest with async register() method
- Deprecate module-level register_node_replacement() function
- Call register_replacements() from comfy_entrypoint()
This enables pyisolate compatibility where extensions run in separate
processes and communicate via RPC. The async API allows registration
calls to cross process boundaries.
Refs: TDD-002
Amp-Thread-ID: https://ampcode.com/threads/T-019c2b33-ac55-76a9-9c6b-0246a8625f21
* fix: remove whitespace and deprecation cruft
Amp-Thread-ID: https://ampcode.com/threads/T-019c2be8-0b34-747e-b1f7-20a1a1e6c9df
a2d4c0f98b