Dataset-oriented loader: folder path, control_after_generate index
(fixed/increment/decrement), depth control, sidecar .txt text output,
alpha->mask, stem filename, resolved index. TDD plan with a pure stdlib
scan layer; self-contained except a merge-aware root __init__ registration
(pool node is being built concurrently).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
