Add wxEVT_CHAR_HOOK event type

[trypsynth]

Summary

• Adds WXD_EVENT_TYPE_CHAR_HOOK, mapped to wxEVT_CHAR_HOOK, following the same pattern as the existing KEY_DOWN/KEY_UP/CHAR event types.
• Includes it in wxd_IsKeyboardEvent so the existing KeyEventData helpers (get_key_code, cmd_down, control_down, and so on) work for it.
• Adds the corresponding EventType::CHAR_HOOK constant on the Rust side.

Motivation

wxEVT_CHAR_HOOK is the standard wxWidgets mechanism for catching a keyboard shortcut at the level of a dialog or frame regardless of which child control currently has focus. A plain KEY_DOWN binding on the top level window only fires when that window itself has focus, not when a child control inside it does, which makes it unsuitable for implementing shortcuts like closing a dialog with Cmd+W. CHAR_HOOK fires before normal key routing and is delivered to the top level window's handler chain first, so it does not have this limitation.

Test plan

• cargo build -p wxdragon succeeds locally.