ModelRelay 0.2.0

Added

• A modelrelay agent skill and Claude Code plugin marketplace, so coding agents in host apps
  add the package, use the docs of their resolved version and follow the SDK's safety contracts.
  make check-skill keeps its guide links and API names in sync with the package.
• Field.Kind.object groups fields, so extract steps and tool parameters can ask for
  lists of records such as .list(.object([...])). Each object reads as a dictionary.
  Exhaustive switches over Field.Kind need a case for it.
• Host tools: HostTools in a HostToolKit, passed as WorkflowExecutor(hostToolKits:), are
  tools the app writes in Swift, such as one that edits the app's own state. Agent and Use a Tool
  steps select them by kit id, so workflows stay Codable. Calls that change something follow the
  write policy; local-only executions may call them.

Fixed

• Named schema nodes no longer share a definition when their names repeat (a tool and one of its
  choice parameters, or fields in different objects), which let one replace the other's shape.