v0.7.0

Added

• Recognised #[app_error(...)] on derived structs and enum variants, capturing
  the mapped AppErrorKind, optional AppCode and whether the formatted
  Display output should become the public message.
• Generated From<Error> implementations that construct masterror::AppError
  (and, when requested, AppCode) by matching on enum variants and invoking
  AppError::with/AppError::bare.

Tests

• Introduced trybuild fixtures covering successful struct/enum conversions and
  compile failures for missing metadata, including message propagation checks in
  the passing cases.

Documentation

• Documented the #[app_error(...)] attribute in the README, outlining the
  struct and enum mapping patterns and the message flag behaviour.