v4.3.0

Added

• #[InputKeyTo(KeyCase::X)] — Input key case conversion. Apply at class level to remap all incoming array keys before hydration, or at property level to override for a specific property. Conversion splits on camelCase/PascalCase boundaries, underscores, hyphens, and whitespace, then rejoins in the target case.
• #[OutputKeyTo(KeyCase::X)] — Output key case conversion. Apply at class level to remap all serialized keys during toArray(true) / toJson(true), or at property level to override for a specific property.
• KeyCase enum — 8 naming conventions: Snake (nick_name), PascalSnake (Nick_Name), Macro (NICK_NAME), Camel (nickName), Pascal (NickName), Kebab (nick-name), CamelKebab (nick-Name), Train (Nick-Name).
• InvalidKeyCaseException — Thrown at definition time when #[InputKeyTo] or #[OutputKeyTo] receives a value that is not a KeyCase enum instance (e.g. a plain string).