fix(kotlin): emit implements edge for interface delegation (by)

[Synvoya]

What it fixes

Kotlin interface delegation — class Foo : Bar by baz — emitted no edge, so the delegated interface Bar was silently dropped from the graph.

The delegation_specifier loop only handled constructor_invocation (→ inherits) and a bare user_type (→ implements) child. The by form produces an explicit_delegation node that wraps the user_type, so neither branch fired and no edge was emitted. Delegation is idiomatic Kotlin (the whole point of by).

Fix

Add an explicit_delegation branch in that loop: take its wrapped user_type child and emit the implements edge, leaving the existing generic type-argument recovery intact.

class LoggingList<T>(inner: MutableList<T>) : MutableList<T> by inner

now emits implements: LoggingList -> MutableList (and references: LoggingList -> T for the generic arg).

Test

• tests/fixtures/sample.kt: added the delegation example above.
• tests/test_languages.py: test_kotlin_interface_delegation_emits_implements asserts the implements edge.
• pytest tests/test_languages.py -k kotlin → 9 passed (negative control without the fix fails on the missing edge).

[safishamsi]

Merged into v8 as 9b04022, with your authorship preserved (ships in 0.9.6). Thanks @Synvoya.

Nice catch on the explicit_delegation wrapper — the by form fell between the constructor_invocation and bare user_type branches so the edge was dropped. Unwrapping to the inner user_type keeps generic-argument recovery working, and implements (not inherits) is the right relation for delegation. Fixture + test made review easy.