feat(mcp,editor): Option A+B storage + 10 agent deliverables (Phase 7)

Ships the combined filesystem/Supabase storage adapter + MCP scene
lifecycle tools + Next.js API routes + editor /scene/[id] route, so
an MCP save is directly openable at /scene/<id> without any
injection hack. End-to-end verified: 10/10 e2e steps pass.

Storage (A1/A2/A3):
- SceneStore interface + error classes + slug helpers
- FilesystemSceneStore at $PASCAL_DATA_DIR (defaults XDG/~/.pascal)
  with atomic writes, .index sidecar, optimistic locking
- SupabaseSceneStore with scenes + scene_revisions tables, RLS
  migration SQL, mock-backed unit tests
- createSceneStore(env) auto-selects based on SUPABASE_URL +
  SUPABASE_SERVICE_ROLE_KEY

MCP tools (A4, A8, A9, A10):
- save_scene / load_scene / list_scenes / delete_scene / rename_scene
- list_templates / create_from_template (3 seed templates:
  empty-studio, two-bedroom, garden-house)
- generate_variants (7 mutation kinds, seeded RNG, save=true|false)
- photo_to_scene (vision sampling → scene graph → save)

Editor (A5, A6):
- /api/scenes + /api/scenes/[id] with RFC 7232 If-Match locking
- /scene/[id] and /scenes route pages with save button, SceneLoader
- Removed the window.__pascalScene dev injection hack

Security + UX edges (A7, A8):
- AssetUrl Zod validator: asset:// blob: data:image/ /path https:
  (http://localhost for dev) + PASCAL_ALLOWED_ASSET_ORIGINS env
  allowlist. Hardens scan.url, guide.url, item.asset.src,
  material.texture.url, MaterialMaps.*Map
- Auto-frame camera on empty→non-empty scene transition
  (camera-controls:fit-scene emitter event)

Shared utilities:
- rehydrateSiteChildren() extracted to packages/mcp/src/lib/ and
  used by both create-from-template and generate-variants to work
  around the SiteNode.children-as-objects vs. ids inconsistency
  (CROSS_CUTTING §2)
- Storage + MCP subpath exports added to packages/mcp/package.json
  (CROSS_CUTTING §4)

Tests: 293 pass / 0 fail across 40 files (was 142 pre-Phase-7).
Biome: clean.

Phase-7 e2e script at packages/mcp/test-reports/phase7-e2e.ts:
MCP HTTP + editor Next.js both point at $PASCAL_DATA_DIR =
/tmp/pascal-e2e, save_scene from MCP, GET /api/scenes/<id> from
editor server, /scenes list page renders all saved scenes, scene
page renders SceneLoader, delete_scene works.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/core/src/index.ts

@@ -1,6 +1,7 @@
 export type {
   BuildingEvent,
   CameraControlEvent,
+  CameraControlFitSceneEvent,
   CeilingEvent,
   DoorEvent,
   EventSuffix,
@@ -37,7 +38,6 @@ export {
   type Space,
   wallTouchesOthers,
 } from './lib/space-detection'
-export { baseMaterial, glassMaterial } from './materials'
 export {
   getCatalogMaterialById,
   getLibraryMaterialIdFromRef,
@@ -48,6 +48,7 @@ export {
   type MaterialCatalogItem,
   toLibraryMaterialRef,
 } from './material-library'
+export { baseMaterial, glassMaterial } from './materials'
 export * from './schema'
 export {
   type ControlValue,
@@ -55,20 +56,14 @@ export {
   useInteractive,
 } from './store/use-interactive'
 export { default as useLiveTransforms, type LiveTransform } from './store/use-live-transforms'
-export { FenceSystem } from './systems/fence/fence-system'
 export { clearSceneHistory, default as useScene } from './store/use-scene'
 export { CeilingSystem } from './systems/ceiling/ceiling-system'
 export { DoorSystem } from './systems/door/door-system'
+export { FenceSystem } from './systems/fence/fence-system'
 export { ItemSystem } from './systems/item/item-system'
 export { RoofSystem } from './systems/roof/roof-system'
 export { SlabSystem } from './systems/slab/slab-system'
 export { StairSystem } from './systems/stair/stair-system'
-export {
-  DEFAULT_WALL_HEIGHT,
-  DEFAULT_WALL_THICKNESS,
-  getWallPlanFootprint,
-  getWallThickness,
-} from './systems/wall/wall-footprint'
 export {
   getClampedWallCurveOffset,
   getMaxWallCurveOffset,
@@ -82,12 +77,18 @@ export {
   normalizeWallCurveOffset,
   sampleWallCenterline,
 } from './systems/wall/wall-curve'
+export {
+  DEFAULT_WALL_HEIGHT,
+  DEFAULT_WALL_THICKNESS,
+  getWallPlanFootprint,
+  getWallThickness,
+} from './systems/wall/wall-footprint'
 export {
   calculateLevelMiters,
   getWallMiterBoundaryPoints,
   type Point2D,
-  type WallMiterBoundaryPoints,
   pointToKey,
+  type WallMiterBoundaryPoints,
   type WallMiterData,
 } from './systems/wall/wall-mitering'
 export { WallSystem } from './systems/wall/wall-system'