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/README.md

@@ -294,23 +294,23 @@ component ancestry.
 
 ## Source layout
 
-The package is layered; each layer depends only on the ones above it.
+Each module depends only on the ones listed above it.
 
-| Directory       | Responsibility                                                                                          |
-| --------------- | ------------------------------------------------------------------------------------------------------- |
-| `shared/`       | Geometry and environment helpers                                                                        |
-| `view/`         | `originView()` component recipes                                                                        |
-| `choreography/` | Effect types, `defineOriginChoreography()`, presets, and `composeEffects()` style compositing           |
-| `actions/`      | `forward()`, `back()`, `replace()`, `above()`, `under()`, `originAction()`                              |
-| `scene/`        | `graph.ts` storage, `transitions.ts` history rules, `compositor.ts` styles, `spring.ts` settling motion |
-| `composables/`  | `useOrigin()` and the node-scope injection key                                                          |
-| `gesture/`      | Builder, definition→policy normalization, start admission, pointer tracking, and the recognizer         |
-| `components/`   | `OriginScene`, `OriginGesture`, `OriginGestureSurface`, and the internal node host                      |
+| File                    | Responsibility                                                                                    |
+| ----------------------- | ------------------------------------------------------------------------------------------------- |
+| `shared.ts`             | Geometry and environment helpers                                                                  |
+| `choreography.ts`       | Effect types, `defineOriginChoreography()`, presets, and `composeEffects()` style compositing     |
+| `navigation.ts`         | `originView()` recipes and `forward()`, `back()`, `replace()`, `above()`, `under()` actions       |
+| `scene/types.ts`        | Public scene types                                                                                |
+| `scene/graph.ts`        | `SceneGraph`: node and edge storage plus the begin/commit/cancel history rules (all synchronous)  |
+| `scene/scene.ts`        | `Scene` and `OperationHandle`: mounting, measuring, settling spring, compositing, and `useOrigin` |
+| `gesture/definition.ts` | Gesture types, component props, and the immutable `gesture` builder                               |
+| `gesture/recognizer.ts` | Pointer-down admission, `DirectionalTracker`, `GestureRecognizer`, and `useOriginGesture`         |
+| `components/`           | `OriginScene`, `OriginGesture`, `OriginGestureSurface`, and the internal node host                |
 
-`createOriginScene()` wires the scene modules together: the graph holds nodes
-and operation edges, transitions rewrite it synchronously when operations
-begin, commit, or cancel, and the scene adds the asynchronous parts (waiting
-for Vue to mount a target, measuring, and running the settling spring).
+Pure helpers used by a class (for example `matchesStart`, `stepSpring`, or
+`composeNodeStyle`) are module-level `export const`s that the class calls, so
+they can be tested directly without widening the class's interface.
 
 ## Current experimental boundaries