feat(scene): battle grid overlay with color and trap VFX stacking

Add configurable square/hex grid in the scene editor (persisted and shown on control/presentation) and keep trap activation effects above trap icons.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/main/foundry/foundryImport.ts

@@ -387,6 +387,7 @@ export async function buildProjectFromFoundryDocuments(
       previewRotationDeg: 0,
       darkenScene: false,
       traps: [],
+      grid: { enabled: false, type: 'square', sizeN: 0.06, color: '#ffffff' },
       media: { videos: [], audios: audioRefs },
       settings: {
         autoplayVideo: previewAssetType === 'video',

app/main/project/zipStore.ts

@@ -51,6 +51,7 @@ import type {
 } from '../../shared/types';
 import { PROJECT_SCHEMA_VERSION } from '../../shared/types';
 import { normalizeMaterialLegend } from '../../shared/types/materialLegend';
+import { DEFAULT_SCENE_GRID, normalizeSceneGrid } from '../../shared/types/sceneGrid';
 import { normalizeSceneTrap } from '../../shared/types/sceneTraps';
 import type { AssetId, GraphNodeId, MaterialId, NpcGroupId, NpcId, NpcRelationId } from '../../shared/types/ids';
 import {
@@ -616,11 +617,13 @@ export class ZipProjectStore {
         previewRotationDeg: 0,
         darkenScene: false,
         traps: [],
+        grid: { ...DEFAULT_SCENE_GRID },
       } satisfies Scene);
 
     const next: Scene = {
       ...base,
       traps: base.traps ?? [],
+      grid: base.grid ?? { ...DEFAULT_SCENE_GRID },
       ...(patch.title !== undefined ? { title: patch.title } : null),
       ...(patch.description !== undefined ? { description: patch.description } : null),
       ...(patch.previewAssetId !== undefined ? { previewAssetId: patch.previewAssetId } : null),
@@ -640,6 +643,7 @@ export class ZipProjectStore {
               .filter((t): t is SceneTrap => Boolean(t)),
           }
         : null),
+      ...(patch.grid !== undefined ? { grid: normalizeSceneGrid(patch.grid) } : null),
       ...(patch.settings ? { settings: { ...base.settings, ...patch.settings } } : null),
       ...(patch.media ? { media: { ...base.media, ...patch.media } } : null),
       ...(patch.layout ? { layout: { ...base.layout, ...patch.layout } } : null),
@@ -2325,6 +2329,7 @@ function normalizeScene(s: Scene): Scene {
   const traps = (Array.isArray(rawTraps) ? rawTraps : [])
     .map((t) => normalizeSceneTrap(t))
     .filter((t): t is SceneTrap => Boolean(t));
+  const grid = normalizeSceneGrid((s as unknown as { grid?: unknown }).grid);
 
   const rawAudios = Array.isArray(raw.audios) ? raw.audios : [];
   const audios = rawAudios
@@ -2354,6 +2359,7 @@ function normalizeScene(s: Scene): Scene {
     previewRotationDeg,
     darkenScene,
     traps,
+    grid,
     layout: layoutIn ?? { x: 0, y: 0 },
     media: {
       videos: raw.videos ?? [],