Document original native reel scenes and visual quality gates

[Hao0321]

Summary

• Add a separate workflow for original chapter explainers and three-source spatial video galleries.
• Use Editkin's own editable geometry, integer-frame motion and UI. Third-party UI components, demo templates and reference media are excluded.
• Check the installed compiler/preset capability before execution; missing source slots, text or frame ranges remain explicit gaps.
• Carry compiled native shapes and declared preset variants through the existing v4 material/design/motion audit and atomic apply workflow.
• Require complete-section visual review, phone readability, output decode and same-generation performance evidence.

Verification

• Changed public text privacy checks passed.
• Full release-selected public privacy gate passed in a clean checkout of this exact commit.
• This is workflow documentation. It does not establish installed product support, full automatic-editing quality or comparative art approval.

Scope is independent from illustrated music MV. Private study media, user footage and project evidence are not published.