ops: publish codeforphilly-data-snapshot public repo (referenced in architecture.md but doesn't exist)

## What's missing

\`specs/architecture.md\` and \`specs/behaviors/storage.md\` both reference a **public scrubbed snapshot** of the data repo — \`codeforphilly-data-snapshot\` — that contributors can clone without needing access to the live production data. The snapshot is supposed to be produced by \`apps/api/scripts/scrub-data.ts\` and pushed periodically.

The scrubber script exists. The public snapshot repo does not.

## Fix shape

Two pieces:

1. **One-time:** create the \`CodeForPhilly/codeforphilly-data-snapshot\` public repo on GitHub; do the first \`scrub-data\` run; push the result.
2. **Recurring:** add a scheduled CI workflow (GitHub Action on a weekly cron, say) that runs the scrub + force-pushes a fresh snapshot tag. Probably lives in \`.github/workflows/\` in this repo since the script lives here.

## Why now

Pre-cutover-onboarding stories assume new contributors can clone the snapshot. If we leave the spec asserting the repo exists without it existing, new contributors hit a dead link.

Identified during the 2026-05-30 post-cutover-blog spec-drift audit.

apps/api/scripts/scrub-data.ts から始め、specs/architecture.md と specs/behaviors/storage.md の参照を読んでください。公開リポジトリ CodeForPhilly/codeforphilly-data-snapshot を作成し、scrubber を実行してその結果を push した後、.github/workflows/ 配下にスケジュールされた workflow を追加してください。snapshot が公開され、初回データが投入され、snapshot tag とともに毎週更新されれば完了です。

索引モデルが issue の本文から書いたものです。