fix(pack): lazy-load sharp and verify unpacked natives

Avoid crashing Electron at startup when sharp is corrupt, and fail pack if asarUnpack natives look truncated.

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

app/main/project/scenePreviewThumbnail.ts

@@ -5,7 +5,8 @@ import path from 'node:path';
 import { promisify } from 'node:util';
 
 import ffmpegStatic from 'ffmpeg-static';
-import sharp from 'sharp';
+
+import { getSharp } from './sharpRuntime.mjs';
 
 const execFileAsync = promisify(execFile);
 
@@ -21,6 +22,7 @@ export async function generateScenePreviewThumbnailBytes(
   kind: 'image' | 'video',
 ): Promise<Buffer | null> {
   try {
+    const sharp = getSharp();
     if (kind === 'image') {
       return await sharp(source)
         .rotate()