Improve the hover rect

[pragmatrix]

• Disable when the a keypress was detected, enable when the mouse was moved.
• Don't move it anymore.
• Hide mouse pointer, too.

[Copilot]

Pull request overview

This PR refines “pointer feedback” behavior (hover rect + cursor visibility) so it can be disabled on keyboard interaction and re-enabled based on subsequent pointer activity, while also simplifying hover-rect motion behavior.

Changes:

• Add a window API wrapper to toggle cursor visibility and cache cursor-visible state in Desktop.
• Add cursor “velocity” detection using recent input history to decide when to re-enable pointer feedback.
• Simplify hover-rect state by removing rect animation (rect is now updated directly while alpha remains animated).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
shell/src/shell_window.rs	Adds set_cursor_visible wrapper for window cursor visibility control.
input/src/event.rs	Adds cursor_has_velocity() helper based on event history.
desktop/src/projects/project_presenter.rs	Removes hover-rect animation; keeps alpha animation and applies rect directly.
desktop/src/event_router.rs	Exposes keyboard_focus_change() to avoid re-querying focus state.
desktop/src/desktop_system.rs	Introduces pointer_feedback_enabled and logic to disable/reenable hover/cursor feedback.
desktop/src/desktop.rs	Caches and applies cursor visibility changes to the shell window.
.github/copilot-instructions.md	Adds guidance about shared state for affordances and caching window state requests.