Data out of public/ (phase 2): posters + tables live in data/

posters/ (42M webp set the poster walls fetch) and tables/ (the merged served
table set — its index.json is the merge; per-profile data/tables remain the
build-time sources) now live in data/ with build copy-steps. Byte parity
verified; served paths unchanged. public/ is now FULLY regenerable — every
source-of-truth folder has a home outside the web-root.

data/README.md

@@ -8,6 +8,8 @@ served web-root by the build (`internal/generate-tree.mjs`), exactly like the pe
 |---|---|---|
 | `people-groups/` | `/assets/people-groups/` | People-group datasets (CSV/JSON) the maps read at runtime |
 | `vendor/` | `/assets/vendor/` | Third-party runtime assets (e.g. table libraries) |
+| `posters/` | `/assets/posters/` | Rendered poster webp set (heavy pipeline output; poster walls fetch these) |
+| `tables/` | `/assets/tables/` | The MERGED served table set (its index.json is the merge; per-profile `app-profiles/*/data/tables` are build-time sources) |
 | `external-bundles/` | `/external/` | Prebuilt map IIFEs vendored from sibling projects (not built here) |
 
 Don't edit anything under `public/` by hand — change it here (or in `app-profiles/*/data/`,