Consolidate core-v2 modules and move scene logic onto classes

- Merge the small modules into 12 files: shared, choreography,
  navigation, scene/{types,graph,scene}, gesture/{definition,recognizer}.
- SceneGraph now owns the begin/update/commit/cancel history rules as
  methods, with the step helpers as private methods.
- createOriginScene returns a markRaw'd Scene class; operation handles
  are an OperationHandle class instead of inline object literals.
- GestureRecognizer gains static create()/policyFor() factories, absorbing
  the separate policy module.
- Pure helpers used by classes (matchesStart, pointOf, stepSpring,
  composeNodeStyle, nodeEffectLayers, shouldCommit, ...) are exported
  consts so they can be tested directly.
- Add haptics tests showing where navigator.vibrate can be triggered.

Public exports, types, and behavior are unchanged; the differential
suites against main still pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Faarh2Ts6StJPcz2mRiHiR

packages/core-v2/src/components/OriginScene.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { onBeforeUnmount, ref, watchEffect } from "vue";
-import type { OriginSceneProps } from "./types";
+import type { OriginSceneProps } from "../scene/types";
 import OriginNodeHost from "./OriginNodeHost.vue";
 
 defineOptions({ name: "OriginScene" });