Cursor preview canvas + appearance controls

Linear: AUT-141

CursorPreviewCanvas reuses the same backend pattern as the editor canvas (CSS fallback / Wisp asset / runtime unavailable) so a pixel- accurate Wisp preview can drop in later without changing the component contract. CursorAppearancePanel composes UI-18 inspector primitives into APPEARANCE / CLICK EFFECT / MOTION / BEHAVIOR sections with a footer (Reset / Apply).

Preview states

Appearance panel states

API

#![allow(unused)]
fn main() {
use ui_storybook::components::cursor::{
    CursorPreviewCanvas, CursorPreviewBackend, CursorAppearancePanel,
};
use ui_storybook::fixtures::cursor::sample_cursor_appearance;

view! {
    <CursorPreviewCanvas backend=CursorPreviewBackend::CssFallback />
    <CursorAppearancePanel view=sample_cursor_appearance() />
}
}