Kotlin func_start misses extension functions with a generic receiver (Collection<X>.name, fun <T> List<T>.name) #3608

Problem

Kotlin function extraction drops extension functions whose receiver type is generic:

Direct StructuralExtractor("kotlin", LANGUAGE_DEFINITIONS).splice(...) on each shape.

Impact

• Function counts, call graph and dead-code signals miss every such function. Kotlin libraries use them heavily: kotlinpoet's joinToCode, asClassName-style helpers.
• Import resolution (Kotlin imports of top-level functions and object members never resolve (import recall 62%) #3596, by declared name) can't find them. kotlinpoet's import com.squareup.kotlinpoet.joinToCode found only a test function of the same name.

Fix direction

The receiver type in func_start needs to accept a bounded generic argument list (<…>, nesting ≤ 2) before the .name(, plus an optional type-parameter list after fun. Follow gitgalaxy/standards/how_to_add_a_language.md (ReDoS rules), add valid/invalid/pathological cases to tests/extraction/languages/test_kotlin.py, and verify with tree_sitter_accuracy_audit.py --lang kotlin.