Kotlin enum entries weren't extracted: the walker never descended into the enum
body (`enum_class_body` wasn't in _KOTLIN_CONFIG.body_fallback_child_types, so
_find_body returned None). Add `enum_class_body` to the fallback body types and a
`_kotlin_extra_walk` (dispatched for tree_sitter_kotlin, mirroring the Java/Swift
handling) that emits each enum_entry as a node with a `case_of` edge to the enum.
Re-applied from PR #1738 (@ivanzhl) onto the post-#1737 module layout: the walk
engine now lives in graphify/extractors/engine.py while _KOTLIN_CONFIG stays in
extract.py. Closes the Kotlin half of #1700 (Java was #1719).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
class Foo : Bar by baz produced no edge because the delegation_specifier loop only handled constructor_invocation and bare user_type children; the by form wraps user_type in an explicit_delegation node. Add that branch so the implements edge (and generic-arg recovery) fires.
