Agent Skills: convert-elm-roc

Bidirectional conversion between Elm and Roc. Use when migrating projects between these languages in either direction. Extends meta-convert-dev with Elm↔Roc specific patterns. Use when migrating Elm frontend code to Roc applications, translating browser-based Elm to platform-agnostic Roc, or refactoring Elm web applications to Roc CLI/native tools. Extends meta-convert-dev with Elm-to-Roc specific patterns.