Transform: scale, rotation and mirror as properties, world transform as a matrix chain, oriented colliders (#76)

Four new rows on sprite, text, collider and container (block TRANSFORM):
scale, rotation in degrees clockwise, mirrorX, mirrorY. As properties they
get override/reset/apply, loading of old projects, write-back after play and
the Properties node for free; camera and behavior have none.

The hierarchy composes T*R*S per level (composeAlongChain replaces
sumAlongChain), so children rotate and scale with their parent. Reparenting
and grouping keep the look (carriedTransform). Drawing goes through
placeNode, the gizmo is a polygon, cull and objectRect use the AABB, drags
are computed in the parent's system.

Colliders are oriented boxes: SAT for box/box, box-circle in the box frame;
exitDistance replaces axisSeparation/axisCorrection, moveAndSlide moves along
the object's own axes.

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

src/runtime/World.ts

@@ -1,4 +1,4 @@
-import { ENTITY_HANDLE, isHandleEnabled, type PointerState, worldPositionOf } from '../core/graph';
+import { ENTITY_HANDLE, isHandleEnabled, type PointerState, worldMatrixOf } from '../core/graph';
 import { newId } from '../core/ids';
 import type { Asset } from '../core/model/Asset';
 import { isPlaceableType } from '../core/model/AssetTypes';
@@ -253,11 +253,11 @@ export class World {
     const parts = [entity, ...this.descendantsOf(entity)].filter((e) => isHandleEnabled(e));
     const colliders = parts.filter((e) => e.type === 'collider');
     if (colliders.length > 0)
-      return colliders.some((c) => shapeContains(colliderShape(c.props, worldPositionOf(c)), point));
+      return colliders.some((c) => shapeContains(colliderShape(c.props, worldMatrixOf(c)), point));
     return parts.some(
       (e) =>
         (e.type === 'sprite' || e.type === 'text') &&
-        footprintContains(e.type, e.props, worldPositionOf(e), point),
+        footprintContains(e.type, e.props, worldMatrixOf(e), point),
     );
   }