feat(traps): activation VFX/SFX, explosion effect, and help section

Wire mimic/pit/arrow/laser media on activate, poison/explosion via effects, and document the scene editor and traps in Instructions.

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

app/renderer/shared/effects/PxiEffectsOverlay.tsx

@@ -57,6 +57,9 @@ function vfxPacksForTool(tool: EffectToolType): readonly VfxFramePack[] {
       return ['sunbeam'];
     case 'poisonCloud':
       return ['poisonCloud'];
+    case 'explosion':
+      // Визуал — HTML `<video>` с альфой (ExplosionVideoOverlay), не кадровый Pixi-pack.
+      return [];
     default:
       return [];
   }
@@ -78,6 +81,8 @@ function vfxPacksForInstanceType(type: EffectInstanceType): readonly VfxFramePac
       return ['sunbeam'];
     case 'poisonCloud':
       return ['poisonCloud'];
+    case 'explosion':
+      return [];
     default:
       return [];
   }
@@ -769,6 +774,13 @@ function createInstanceNode(
     redrawPoisonCloud(cont, inst, viewport, 0, Math.max(1, inst.lifetimeMs));
     return cont;
   }
+  if (inst.type === 'explosion') {
+    // Визуал рисует ExplosionVideoOverlay (WebM с альфой). Pixi-нода — только placeholder.
+    const cont = new pixi.Container();
+    cont.visible = false;
+    (cont as any).__fx = { id: inst.id, type: inst.type };
+    return cont;
+  }
   if (inst.type === 'freeze') {
     const tex = getFreezeScreenTexture(pixi, inst.seed, viewport);
     const s = new pixi.Sprite(tex);
@@ -988,6 +1000,12 @@ function animateNodes(
       redrawPoisonCloud(cont, inst, viewport, t, life);
     }
 
+    if (inst.type === 'explosion') {
+      // Визуал — ExplosionVideoOverlay; Pixi-placeholder остаётся скрытым.
+      node.visible = false;
+      continue;
+    }
+
     if (inst.type === 'freeze') {
       const s = node;
       const life = Math.max(1, inst.lifetimeMs);
@@ -1776,6 +1794,9 @@ function instanceContentSig(inst: EffectInstance): string {
   if (inst.type === 'poisonCloud') {
     return `pc:${Math.round(inst.at.x * 1000)}:${Math.round(inst.at.y * 1000)}:${Math.round(inst.radiusN * 1000)}`;
   }
+  if (inst.type === 'explosion') {
+    return `ex:${Math.round(inst.at.x * 1000)}:${Math.round(inst.at.y * 1000)}:${Math.round(inst.radiusN * 1000)}`;
+  }
   if (inst.type === 'freeze') {
     return `fr:${Math.round(inst.at.x * 1000)}:${Math.round(inst.at.y * 1000)}:${Math.round(inst.intensity * 1000)}`;
   }
@@ -1913,6 +1934,11 @@ function relayoutInstanceNode(
     return true;
   }
 
+  if (inst.type === 'explosion') {
+    node.visible = false;
+    return true;
+  }
+
   if (inst.type === 'freeze') {
     const fx = (node as any).__fx ?? {};
     if (fx.vw !== viewport.w || fx.vh !== viewport.h) {