Trigger colliders and Move and slide against solid colliders

- Collider property isTrigger (no blocking, still reports enter/stay/exit)
- Node 'Move and slide' with blocked x/y outputs, axis-wise resolution
- axisSeparation/axisCorrection geometry for box/box, circle/circle, box/circle
- Amber outline for trigger colliders in the viewport
- Demo mover uses Move and slide; E2E step 15b, 7 new unit tests

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/viewport/Viewport.ts

@@ -5,7 +5,7 @@ import { type Position, type PropertyBag, sortByZ, type Vec2 } from '../core/mod
 import { treeOrder, worldPosition } from '../core/model/hierarchy';
 import { findAsset } from '../core/model/Project';
 import { cameraFrame, rectAround, rectsIntersect, type WorldRect } from '../core/properties/camera';
-import { colliderShape, colliderSize } from '../core/properties/collider';
+import { colliderShape, colliderSize, isTrigger } from '../core/properties/collider';
 import { resolveSceneObjectProps } from '../core/properties/resolve';
 import type { World } from '../runtime/World';
 import { Theme, textStyle, Widget, type Size } from '../ui';
@@ -305,7 +305,8 @@ export class Viewport extends Widget {
         const shape = colliderShape(item.props, { x: 0, y: 0 });
         if (shape.kind === 'circle') node.circle(0, 0, shape.r);
         else node.rect(-shape.w / 2, -shape.h / 2, shape.w, shape.h);
-        node.fill({ color: Theme.colors.collider, alpha: 0.12 }).stroke({ width: 2 / view.scale, color: Theme.colors.collider });
+        const color = isTrigger(item.props) ? Theme.colors.trigger : Theme.colors.collider;
+        node.fill({ color, alpha: 0.12 }).stroke({ width: 2 / view.scale, color });
       }
     }
     this.drawParentLinks(items, editing, view.scale);