arxiv pdf: download to temp file then move, so a failed download no
longer poisons re-entry with a corrupt partial file. e-print tar:
--max-size is not a GNU tar option and silently did nothing; extract
first then audit with du, failing if >50M.
Attach the stepwise derivation toolkit as a submodule and default
SUPERPAPER_PHASE to 2 so rewrite-figure can use superderive. Notes
still keep align for short expansions without cancel or subst.
Add the ledger schema, class router, lint codes, ingest/build
pipeline, and three work-tree examples: align derivation,
superfig delegation, and supertensor delegation.
House the two figure toolkits as git submodules under SuperPaper.
The parent owns paper-note orchestration; children keep their own
history, macros, and lint. DESIGN.md is the family contract.