Agent Skills: convert-elixir-scala

Bidirectional conversion between Elixir and Scala. Use when migrating projects between these languages in either direction. Extends meta-convert-dev with Elixir↔Scala specific patterns. Use when migrating Elixir/Phoenix applications to Scala, translating BEAM OTP patterns to Akka actors, or refactoring dynamic concurrency to statically-typed JVM patterns. Extends meta-convert-dev with Elixir-to-Scala specific patterns.