jextract/jni: Enum case record names can collide with enclosing types #944

Problem

JNI enum extraction capitalizes each Swift case name to generate a nested Java record. That record can have the same name as its enum, another enclosing type, or the generated Case interface. Java rejects these declarations because a nested type cannot share an enclosing type's name.

Example

public enum Message {
  case message(Int64)
}

The generated Java code contains a record named Message inside Message.Case. This conflicts with the enclosing Message type and causes Java compilation to fail.

The generated record name should avoid collisions with enclosing types. Its payload accessor and case dispatch should use the same name consistently.

Reference workaround implementation: qoncept#7