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/runtime/systems/CollisionSystem.ts

@@ -1,3 +1,4 @@
+import { isHandleEnabled } from '../../core/graph';
 import { type Axis, axisCorrection, colliderShape, colliderSize, isTrigger, shapesOverlap } from '../../core/properties/collider';
 import type { Entity } from '../Entity';
 import type { World } from '../World';
@@ -27,7 +28,8 @@ export class CollisionSystem implements System {
   private previous = new Map<string, CollisionPair>();
 
   update(world: World): void {
-    const colliders = world.entities.filter((e) => e.type === 'collider');
+    // Switched-off colliders (or ones below something switched off) take no part at all.
+    const colliders = world.entities.filter((e) => e.type === 'collider' && isHandleEnabled(e));
     const current = new Map<string, CollisionPair>();
     for (let i = 0; i < colliders.length; i++) {
       for (let j = i + 1; j < colliders.length; j++) {
@@ -77,8 +79,8 @@ export class CollisionSystem implements System {
    * colliders and colliders that travel with it (descendants) never block.
    */
   moveAndSlide(world: World, entity: Entity, dx: number, dy: number): { blockedX: boolean; blockedY: boolean } {
-    const own = collidersOf(world, entity).filter((c) => !isTrigger(c.props));
-    const obstacles = own.length === 0 ? [] : world.entities.filter((c) => c.type === 'collider' && !isTrigger(c.props) && !this.travelsWith(c, entity));
+    const own = collidersOf(world, entity).filter((c) => !isTrigger(c.props) && isHandleEnabled(c));
+    const obstacles = own.length === 0 ? [] : world.entities.filter((c) => c.type === 'collider' && !isTrigger(c.props) && isHandleEnabled(c) && !this.travelsWith(c, entity));
     return { blockedX: this.slideAxis(world, entity, own, obstacles, 'x', dx), blockedY: this.slideAxis(world, entity, own, obstacles, 'y', dy) };
   }
 
@@ -155,5 +157,5 @@ export function bodyOf(collider: Entity): Entity {
 /** A collider stands for itself; any other entity stands for its direct collider children. */
 export function collidersOf(world: World, entity: Entity): Entity[] {
   if (entity.type === 'collider') return [entity];
-  return world.childrenOf(entity).filter((e) => e.type === 'collider');
+  return world.childrenOf(entity).filter((e) => e.type === 'collider' && isHandleEnabled(e));
 }