fix(kotlin): resolve qualified supertype to its tail type name

[Synvoya]

Bug

A Kotlin class with a qualified supertype resolves its heritage edge to the package root instead of the type. class Foo : com.example.Base() emits Foo --inherits--> com instead of Foo --inherits--> Base, collapsing every qualified base/interface onto a bogus com node.

Root cause

_kotlin_user_type_name returned the first identifier child of a user_type node. The tree-sitter-kotlin grammar stores a qualified name as flat identifier children:

user_type "com.example.Base"
  identifier "com"
  .
  identifier "example"
  .
  identifier "Base"

So the walker returned com.

Minimal repro

class Foo : com.example.Base(), com.example.Iface

Before: inherits {(Foo, com)}, implements {(Foo, com)}.

Fix

Scan the direct children and keep the last identifier/type_identifier segment. Type arguments live in a separate type_arguments child (not an identifier), so generics like com.ex.Container<String> correctly resolve to Container. This mirrors the existing C++ qualified-base handling that uses the unqualified tail. Simple (Base) and delegated (Bar by baz) supertypes are unaffected — a single-segment user_type still returns that segment.

After the fix:

• Foo --inherits--> Base
• Foo --implements--> Iface

Testing

• Added test_kotlin_qualified_supertype_uses_tail_name to tests/test_languages.py. Fails before, passes after.
• tests/test_languages.py: 315 passed, 13 skipped — the existing Kotlin simple-supertype and interface-delegation tests still pass.