Package the anonymous supplementary artifact

[duckyquang]

Execute paper/ANONYMIZATION.md end to end: build the scrubbed supplementary zip (code + tests + citable results + README quickstart, excluded files per section 2, sed pass per section 3, PROVENANCE branch-column substitution per section 4). Verify by grepping the ZIP CONTENTS for every name/handle on the checklist (zero hits) and by running the fast tests inside a fresh unzip. Produce dist/marc_supplementary.zip + a one-page SUPPLEMENTARY_README inside it.

Do this twice: a dry run early in the week (finds checklist gaps while there is time), the real one after #122 freezes the paper. Est 1 day total.

[duckyquang]

Status: the packaging is fully automated and the dry run is CLEAN as of quang/pre-freeze-fixes — scripts/make_supplementary.sh now emits dist/marc_supplementary.zip (880K) per this issue's spec, excludes itself from the artifact (its sed patterns carry every name it scrubs), and the branch-name scrub covers every shipped text file, not just PROVENANCE. The Jul-27 merges had introduced one new leak (paper/structure_invention_negative.md citing a personal branch) — caught by the dry run and now scrubbed. Remaining: the one real packaging run after #122 freezes the paper — a single bash scripts/make_supplementary.sh at the freeze commit.