refactor: migrate core DOM tree interfaces

[jderochervlk]

Tracking issue: #342

Summary

• migrate core node, element, range, traversal, selection, and character-data APIs onto DOMTree
• add focused interface modules including Attr, AbstractRange, StaticRange, CDATASection, and ProcessingInstruction
• move interface-specific operations out of the broad type modules

Temporary state

• the DOMTree types used here are still aliases to the old recursive definitions from refactor: introduce DOMTree compatibility foundation #301
• some shared option and helper types continue to come from DomTypes so this layer compiles independently
• refactor: remove DOM compatibility types #310 makes DOMTree concrete, relocates the remaining helpers, and deletes DomTypes

Review focus

• recursive type relationships and public method signatures
• completeness of each newly owning interface module
• absence of behavioral changes beyond type ownership

Verification

• npm run build
• npm test
• npm run format:check

[jderochervlk]

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