Enabled switch, text assets, mouse input and the jump-and-run example game

Engine additions that the example game needed:
- `enabled` as a shared property of every placeable asset (default on, an
  override on the scene object). A switched-off object is not drawn, does not
  collide and its behavior does not run - and neither does anything parented
  below it. Disabled objects are now hidden in the scene view as well, so the
  editor shows what the game shows; they stay in the hierarchy panel, which is
  where they are selected and switched back on.
- Asset type `text` (text, fontSize, color, align), rendered in scene and game.
- Pointer input in the game view: `On click`, `Mouse position`, `Mouse button`,
  `Is hovered`, hit-tested against colliders, else sprite/text footprints.
- New nodes: Set/Is enabled, Set text, Is asset, Name of, Equals, To text,
  Join text, Floor/Ceil/Round, Modulo, Random, Time, Restart game.

Tooling: shared CDP harness (tools/harness.mjs), central project registry with
a guard that keeps destructive scripts off the playground (tools/projects.mjs),
plus smoke suites for the demo scene and the jump-and-run game.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/properties/collider.ts

@@ -27,6 +27,12 @@ export function colliderSize(props: PropertyBag): { w: number; h: number } {
   return shape.kind === 'circle' ? { w: shape.r * 2, h: shape.r * 2 } : { w: shape.w, h: shape.h };
 }
 
+/** Whether a point lies inside a shape (used for pointer hit tests). */
+export function shapeContains(shape: ColliderShape, point: Vec2): boolean {
+  if (shape.kind === 'circle') return (point.x - shape.x) ** 2 + (point.y - shape.y) ** 2 <= shape.r * shape.r;
+  return Math.abs(point.x - shape.x) * 2 <= shape.w && Math.abs(point.y - shape.y) * 2 <= shape.h;
+}
+
 /** Whether two shapes overlap. Shapes that merely touch along an edge do not overlap. */
 export function shapesOverlap(a: ColliderShape, b: ColliderShape): boolean {
   if (a.kind === 'box' && b.kind === 'box') {