Trigger colliders and Move and slide against solid colliders

- Collider property isTrigger (no blocking, still reports enter/stay/exit)
- Node 'Move and slide' with blocked x/y outputs, axis-wise resolution
- axisSeparation/axisCorrection geometry for box/box, circle/circle, box/circle
- Amber outline for trigger colliders in the viewport
- Demo mover uses Move and slide; E2E step 15b, 7 new unit tests

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

tests/core/graph.test.ts

@@ -26,6 +26,11 @@ function context(overrides: Partial<NodeContext> = {}): NodeContext & { logs: st
     findByName: () => null,
     isKeyDown: () => false,
     isTouching: () => false,
+    moveAndSlide: (target: EntityHandle, dx: number, dy: number) => {
+      target.x += dx;
+      target.y += dy;
+      return { blockedX: false, blockedY: false };
+    },
     log: (m: string) => logs.push(m),
     destroy: () => {},
     stop: () => { ctx.stopped = true; },