Slate v2 Phase 9 UI / Layout Families

Supporting plan. For current queue and roadmap truth, see master-roadmap.md.

Goal

Sharpen the remaining UI/layout bucket with cheap legacy-only comparison rows.

Scope

• add legacy-only comparison rows for:
  • forced-layout
  • styling
  • hovering-toolbar
• update the family ledger so these stop living in one vague bucket

Constraints

• no fake current v2 family claims
• keep scroll-into-view out unless a stable row exists
• use the matrix as evidence, not as a promise

Progress

• added legacy-only comparison rows for:
  • forced-layout
  • styling
  • hovering-toolbar
• proved the expanded matrix through the cross-repo local runner
• split these families out of the vague later bucket in the family ledger
• left scroll-into-view intentionally later because there is still no stable row for it here
• synced the scoreboard and top-level roadmap/docs
• verification:
  • bash ./scripts/run-cross-repo-local.sh 3010 /examples/rich-inline ../slate 3210 /examples/forced-layout "yarn build:slate-browser:playwright && yarn exec playwright test playwright/integration/examples/replacement-compatibility.test.ts --project=chromium --workers=1"