docs(dw-demo-pim): per-product-type editor tabs, query list preset cells, side-by-side translation worklist (5.8.9)

[Justinvolved]

Folds three measured PIM screen and worklist learnings (DW 10.29.6):

• Per-product-type editor tabs from one ScreenLayout; without a catch-all group unplaced editors vanish. One layout with a tab per category shows each product type its own tab, because a tab whose editors the product lacks is not rendered. Always one IsCatchAll group, unique group names; Order renumbering, delete cascade, no recycle needed. New section in screen-authoring.md, reconciled with the existing dropped-tab diagnostic.
• Query list presets show headers but empty cells. Row data is mapped from the user's own default ProductListScreen preset, not the query's ListScreenViewPresetId. Workaround: a per-user default list preset covering every query column (one CustomFields| column, each CategoryFields| column listed). New section in screen-authoring.md.
• Translation widget that opens side by side. Query edit-screen languages plus Open product in edit mode open Multi Edit; ProductQueryListWidget is hidden from the picker but added by system name and has product-aware rows. Recipe in dw-demo-pim localization.md, widget row in rules-and-dashboards.md.

Version 5.8.9. validate-skills.py exits 0 and build-manifest.mjs --check is clean.