Support raw generic types in native headers

[kindlich]

Summary

• Raw types in native headers: a raw class reference such as a GenClass parameter used to crash with Could not find type variable T. The converter looked up the class's own type variables, which are only in scope when the class refers to itself. Raw types are now erased the way Java does it: each type argument becomes out <erasure of its first bound>. So a raw Something<T extends Parent> exposes Parent's members, and an unbounded T becomes out Object. Bounds that lead back to the class being loaded (e.g. T extends Node<T>) become Object. Like JavaRuntimeClass.translateTypeParameters, this uses the TypeVariableContext as the guard: the type variables are put into a child context before their bounds are resolved.
• Backend wildcard fix: JavaTypeInternalNameVisitor mapped every out X wildcard to java/lang/Object, so values typed out Parent were checkcast to Object, and calling Parent methods on them failed bytecode verification (VerifyError). This also affected explicit ? extends Parent parameters, not just raw types. JavaTypeDescriptorVisitor.visitWildcardOut also called itself instead of the bound. Both now use the upper bound. Both fixes are needed for bounded raw types to work end-to-end, so they're in one PR.

Testing

• RawTypeInHeaderTest.testRawTypeErrors1/2 (added in e0851bc as a known failure) now pass.
• New RawBoundedTypeInHeaderTest covers a raw bounded parameter accepting BoundedGenClass<Child> and a raw bounded return type exposing the bound's members at runtime.
• New RawRecursiveBoundTypeInHeaderTest round-trips a raw self-bounded type. It's a separate class so that a failure points only at the recursion guard. Mutation-checked: with the guard disabled, only this test fails.
• ./gradlew test --rerun-tasks: 1,043 tests, 0 failures.

Limitation: only the first bound is used, so T extends A & B becomes out A, matching Java's erasure.

Stacked on #190 (which is stacked on #191).

🤖 Generated with Claude Code