feat: add macOS ad-hoc signing support

- Implemented afterPack script to ensure ad-hoc signature for macOS builds.
- Created macosSignUtils module to handle app path retrieval, signature inspection, and ad-hoc signing.
- Added functions to check if the app is signed and apply ad-hoc signing if necessary.

scripts/desktop/macosSignUtils.mjs

@@ -0,0 +1,41 @@
+import { execFile } from 'node:child_process';
+import { promisify } from 'node:util';
+
+const execFileAsync = promisify(execFile);
+
+export function getMacAppPath(context) {
+  return `${context.appOutDir}/${context.packager.appInfo.productFilename}.app`;
+}
+
+export async function inspectSignature(appPath) {
+  try {
+    const { stdout, stderr } = await execFileAsync('codesign', ['-dv', '--verbose=4', appPath]);
+    const output = `${stdout}\n${stderr}`;
+    return {
+      signed: true,
+      isAdHoc: /Signature=adhoc/i.test(output) || !/Authority=/i.test(output),
+      details: output,
+    };
+  } catch {
+    return {
+      signed: false,
+      isAdHoc: false,
+      details: '',
+    };
+  }
+}
+
+export async function adHocSign(appPath) {
+  await execFileAsync('codesign', ['--force', '--deep', '--sign', '-', appPath]);
+}
+
+export async function ensureAdHocSignature(appPath) {
+  const signature = await inspectSignature(appPath);
+  if (signature.signed) {
+    return signature;
+  }
+
+  console.log('[metapi-desktop] No macOS signing identity detected, applying ad-hoc signature.');
+  await adHocSign(appPath);
+  return inspectSignature(appPath);
+}