feat(editor): integrate project hub and launcher

[ZhangchengCharles]

What changed

• add the persistent multi-project Editor Hub and installed editor launcher
• synchronize the editor/runtime protocol surfaces
• complete the repository-wide motion graphics rename

Why it changed

• make registered Cut as Code projects discoverable and directly openable from the packaged editor
• keep the integration branch aligned with the latest editor branch and terminology

How it was checked

• git diff --check origin/feat/integration...origin/feat/video-editor-ui
• UI TypeScript check with incremental output disabled
• repository-wide tracked old-name and path scan

Note: Python is not installed in the current environment, so Python suites were not rerun in this final integration pass.