Slate v2 Node Utility Surface Recovery

Goal

Recover the missing Node / Element / Text utility breadth so the public node API is not a docs-only fantasy.

Completed

• restored the wider Text.* helper surface:
  • isTextList
  • isTextProps
  • matches
  • decorations
• restored the wider Element.* helper surface:
  • isAncestor
  • isElementList
  • isElementProps
  • isElementType
  • matches
• replaced the Node.* stub with the broader traversal/retrieval/check/text surface:
  • ancestor
  • ancestors
  • child
  • children
  • common
  • descendant
  • descendants
  • elements
  • extractProps
  • first
  • fragment
  • get
  • getIf
  • has
  • isAncestor
  • isEditor
  • isElement
  • isNode
  • isNodeList
  • isText
  • last
  • leaf
  • levels
  • matches
  • nodes
  • parent
  • string
  • texts
• widened snapshot-contract.ts to prove traversal, pass pruning, fragment slicing, text decoration splitting, and the main type-guard helpers

Verification

• yarn test:custom
• yarn lint:typescript