fix(electron): Fix broken symlinks in server bundle preventing app startup

Fixes #742

This commit resolves two critical issues that prevented the Electron app from starting:

1. **Broken symlinks in server bundle**
   - After npm install, local @automaker/* packages were symlinked in node_modules
   - These symlinks broke after electron-builder packaging since relative paths no longer existed
   - Solution: Added Step 6b in prepare-server.mjs to replace symlinks with real directory copies
   - Added lstatSync and resolve imports to support symlink detection and replacement

2. **electronUserDataWriteFileSync fails on first launch**
   - The userData directory doesn't exist on first app launch
   - Writing .api-key file would fail with ENOENT error
   - Solution: Added directory existence check and creation with { recursive: true } before writing

Files modified:
- apps/ui/scripts/prepare-server.mjs: Added symlink replacement logic after npm install
- libs/platform/src/system-paths.ts: Added parent directory creation in electronUserDataWriteFileSync

Verification: After these fixes, npm run build:electron produces a working app that starts without ERR_MODULE_NOT_FOUND errors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

libs/platform/src/system-paths.ts

@@ -750,6 +750,11 @@ export function electronUserDataWriteFileSync(
     throw new Error('[SystemPaths] Electron userData path not initialized');
   }
   const fullPath = path.join(electronUserDataPath, relativePath);
+  // Ensure parent directory exists (may not exist on first launch)
+  const dir = path.dirname(fullPath);
+  if (!fsSync.existsSync(dir)) {
+    fsSync.mkdirSync(dir, { recursive: true });
+  }
   fsSync.writeFileSync(fullPath, data, options);
 }