Autoformat Runtime Alignment Execution

Goal

Complete Lane 1: autoformat runtime alignment and extension.

Execution Slice

Ship the smallest real closure that satisfies the lane instead of dragging it into another planning loop:

1. lock current-kit truth-table gaps in tests
2. move clearly shared heading/mark rules into @platejs/autoformat
3. keep app-owned quirks explicit:
   • blockquote wrap
   • list and condensed todo shorthand
   • immediate code-fence promotion
   • immediate HR insertion
   • code-block gating
4. tighten public docs so autoformat stops pretending every shorthand is one generic package feature

Touchpoints

• packages/autoformat/src/lib/rules/**
• packages/autoformat/src/lib/__tests__/withAutoformat/**
• apps/www/src/registry/components/editor/plugins/autoformat-kit.tsx
• apps/www/src/registry/components/editor/plugins/autoformat-classic-kit.tsx
• apps/www/src/__tests__/package-integration/autoformat/**
• content/(plugins)/(functionality)/autoformat.mdx
• lane-close docs if verification is good

Verification Target

• package tests for heading / mark / text rule families
• app integration tests for current-kit precedence, code-fence, HR, and code-block gating
• build/typecheck/lint for touched code

Progress

• [done] Added shared @platejs/autoformat exports for heading shorthand and inline mark autoformat.
• [done] Rewired the app kits so package-owned rules and app-owned shorthand are visibly separate.
• [done] Added package and app truth-table coverage for:
  • heading shorthand
  • mark autoformat
  • stronger text substitution rows
  • current-kit precedence for ==
  • current-kit code-fence promotion
  • current-kit HR insertion
  • code-block gating
• [done] Updated public /docs/autoformat docs to state the ownership split and keep link automd outside the generic autoformat family.
• [done] Closed the autoformat lane in the editor-behavior roadmap docs.