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/optimizeImageImport.lib.mjs

@@ -2,7 +2,7 @@
  * Visually lossless re-encode for imported raster images (same pixel dimensions).
  * Node-only; shared by the main app and ../project-converter (monorepo sibling).
  */
-import sharp from 'sharp';
+import { getSharp } from './sharpRuntime.mjs';
 
 /** @typedef {import('node:buffer').Buffer} Buffer */
 
@@ -102,6 +102,7 @@ function makePassthrough(buf, meta) {
  * @param {number} h0
  */
 async function sameDimensionsOrThrow(outBuf, w0, h0) {
+  const sharp = getSharp();
   const m = await sharp(outBuf).metadata();
   if ((m.width ?? 0) !== w0 || (m.height ?? 0) !== h0) {
     const err = new Error('encode changed dimensions');
@@ -120,6 +121,13 @@ export async function optimizeImageBufferVisuallyLossless(src) {
     return makePassthrough(input, { width: 0, height: 0, format: 'png' });
   }
 
+  let sharp;
+  try {
+    sharp = getSharp();
+  } catch {
+    return makePassthrough(input, null);
+  }
+
   let meta0;
   try {
     meta0 = await sharp(input, { failOn: 'error', unlimited: true }).metadata();