* pipelines.py: /v1/pipelines/* (image-to-video, story, video-dub, audio-dub)
  chained their steps by calling the image/video/text/TTS handlers DIRECTLY
  in-process, forcing every modality onto whichever engine received the pipeline
  request. In a multi-engine deployment each model may live on a different engine.
  Route every sub-step through the front via execute_api_request (same fix as
  characters/environments) so each lands on the engine that owns that model;
  in-process fallback for single-process mode. Drops the unused TestClient import.

* supervisord.conf: the bundled tools (video_editor, videogen, township) now use
  --base-url http://127.0.0.1:8776 — the PUBLIC nginx port — so they talk to
  coderai exactly like any external client (nginx already proxies the full API
  with 4G bodies / 1h timeouts). The front's own bind stays CODERAI_PORT=18776.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RdMufYvtTbtGDWsiZVoXce