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/BehaviorSystem.ts

@@ -1,4 +1,4 @@
-import { type EntityHandle, GraphInterpreter, type NodeContext, type TraceListener } from '../../core/graph';
+import { type EntityHandle, GraphInterpreter, isHandleEnabled, type NodeContext, type TraceListener } from '../../core/graph';
 import { findAsset, type Project } from '../../core/model/Project';
 import type { Entity } from '../Entity';
 import type { World } from '../World';
@@ -44,12 +44,14 @@ export class BehaviorSystem implements System {
 
   /**
    * One instance per behavior entity: entities that appeared (placed while playing) get an
-   * interpreter and their `On start`; instances whose entity is gone are dropped.
+   * interpreter and their `On start`; instances whose entity is gone are dropped. A behavior
+   * that is switched off has no instance yet – it gets one, and its `On start`, the moment it
+   * is switched on. That is what lets a hidden screen wake up when it is shown.
    */
   private syncInstances(world: World): void {
     this.instances = this.instances.filter((i) => world.entities.includes(i.entity));
     for (const entity of world.entities) {
-      if (entity.type !== 'behavior' || this.instances.some((i) => i.entity === entity)) continue;
+      if (entity.type !== 'behavior' || !isHandleEnabled(entity) || this.instances.some((i) => i.entity === entity)) continue;
       const asset = findAsset(this.project, entity.assetId);
       if (!asset || asset.type !== 'behavior') continue;
       const trace: Trace = { edges: new Map(), nodes: new Map() };
@@ -66,6 +68,7 @@ export class BehaviorSystem implements System {
     const keyOf = (node: { params: Record<string, unknown> }) => String(node.params.key ?? '');
     for (const instance of this.instances) {
       if (!world.entities.includes(instance.entity)) continue; // destroyed during play
+      if (!isHandleEnabled(instance.entity)) continue; // switched off (itself or a parent)
       this.run(instance, (i, ctx) => {
         for (const key of this.input.justPressed) i.fire('OnKeyDown', ctx, {}, (n) => keyOf(n) === key);
         for (const key of this.input.justReleased) i.fire('OnKeyUp', ctx, {}, (n) => keyOf(n) === key);
@@ -81,6 +84,10 @@ export class BehaviorSystem implements System {
           }
         }
         this.fireCollisions(instance, i, ctx);
+        const pointer = world.pointer;
+        if (pointer.pressed && world.hitTest(instance.entity.parent ?? instance.entity, pointer.x, pointer.y)) {
+          i.fire('OnClick', ctx, { x: pointer.x, y: pointer.y });
+        }
         i.fire('OnUpdate', ctx, { dt });
       }, dt);
     }
@@ -144,6 +151,11 @@ export class BehaviorSystem implements System {
       dt,
       findByName: (name) => world.findByName(name) ?? null,
       isKeyDown: (key) => this.input.isDown(key),
+      pointer: world.pointer,
+      hitTest: (target, x, y) => {
+        const found = world.entities.find((e) => e === target || e.id === target.id);
+        return Boolean(found && world.hitTest(found, x, y));
+      },
       isTouching: (a, b) => {
         const ea = world.entities.find((e) => e === a || e.id === a.id);
         const eb = world.entities.find((e) => e === b || e.id === b.id);
@@ -172,6 +184,9 @@ export class BehaviorSystem implements System {
       stop: () => {
         world.stopRequested = true;
       },
+      restart: () => {
+        world.restartRequested = true;
+      },
     };
   }