Agent Skills: convert-elm-haskell

Bidirectional conversion between Elm and Haskell. Use when migrating projects between these languages in either direction. Extends meta-convert-dev with Elm↔Haskell specific patterns. Use when migrating Elm frontend code to Haskell, translating Elm patterns to idiomatic Haskell, or refactoring Elm codebases. Extends meta-convert-dev with Elm-to-Haskell specific patterns.