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/core/graph/NodeContext.ts

@@ -1,6 +1,8 @@
-import type { PropertyBag } from '../model/Properties';
-import { sumAlongChain } from '../model/walk';
+import type { Mat } from '../model/matrix';
+import type { Position, PropertyBag } from '../model/Properties';
+import { type ChainTransform, composeAlongChain } from '../model/walk';
 import { enabledAlongChain } from '../properties/enabled';
+import { localMatrixOf, positionOf, transformOf } from '../properties/transform';
 
 /**
  * Marks a live entity apart from a struct value: both reach a data edge as an object. A symbol
@@ -26,14 +28,23 @@ export interface EntityHandle {
   parent: EntityHandle | null;
 }
 
-export function worldPositionOf(handle: EntityHandle): { x: number; y: number; z: number } {
-  return sumAlongChain(
+/** Position, rotation, scale and mirror of every ancestor applied, nearest last. */
+export function worldTransformOf(handle: EntityHandle): ChainTransform {
+  return composeAlongChain(
     handle,
     (h) => h.parent,
-    (h) => h,
+    (h) => ({ m: localMatrixOf(h, transformOf(h.props)), z: h.z }),
   );
 }
 
+export function worldMatrixOf(handle: EntityHandle): Mat {
+  return worldTransformOf(handle).m;
+}
+
+export function worldPositionOf(handle: EntityHandle): Position {
+  return positionOf(worldTransformOf(handle));
+}
+
 /** Whether a handle and every ancestor of it are switched on. */
 export function isHandleEnabled(handle: EntityHandle): boolean {
   return enabledAlongChain(