[Gui] Add scroll event and additional key constants to GGUI events

[Azmisov]

Adds additional GLFW event integration for the new GGUI interface:

1. Mouse wheel/scroll events are listened for. With the new GGUI interface, mouse move events are not published in get_events, instead users rely on polling the current mouse position. I follow this same pattern, where scroll delta can be polled using get_scroll_delta.
2. Additional common GLFW key constants are provided. Additionally, all other keys are sent as their raw key code, to allow users to lookup any other keys that don't have builtin constants.

---

Note

Medium Risk
Touches low-level GLFW input plumbing and changes how unknown key codes are surfaced (now emitting Key_<id> events instead of dropping them), which could affect event handling for some apps. Overall scope is contained to GGUI input and Python bindings.

Overview
Adds scroll-wheel support to GGUI by wiring GLFW scroll callbacks through InputHandler/WindowBase and exposing a new poll-style Python API Window.get_scroll_delta() (via pybind) that returns accumulated (dx, dy) and resets after read.

Expands supported key constants (function, navigation, numpad) on both the C++ and Python sides, improves digit key name/id conversion, and changes unknown key handling to produce events with a Key_<id> string instead of throwing/dropping the event.

^{Written by Cursor Bugbot for commit 087062c. This will update automatically on new commits. Configure here.}