fix: support GTM and tag managers via window.pulseConfig fallback

Script detection now also searches by src URL and supports a global
config object (window.pulseConfig) for environments where data-*
attributes are not preserved on the injected script element.

lib/integration-guides.tsx

@@ -2298,15 +2298,32 @@ export default defineConfig({
       <p>Follow these steps to add Pulse through GTM:</p>
       <ol>
         <li>Go to <strong>Tags &rarr; New &rarr; Custom HTML</strong></li>
-        <li>Paste the Pulse script</li>
+        <li>Paste the snippet below (replace <code>your-site.com</code> with your domain)</li>
         <li>Set the trigger to <strong>All Pages</strong></li>
         <li>Publish your container</li>
       </ol>
-      <CodeBlock filename="GTM → Custom HTML Tag">{`<script
+      <CodeBlock filename="GTM → Custom HTML Tag (recommended)">{`<script>
+  window.pulseConfig = { domain: "your-site.com" };
+</script>
+<script defer src="https://pulse.ciphera.net/script.js"></script>`}</CodeBlock>
+
+      <p>
+        This uses a global config object so that GTM does not need to preserve{' '}
+        <code>data-*</code> attributes on the injected script element. You can
+        also pass <code>api</code>, <code>storage</code>, and other options via{' '}
+        <code>pulseConfig</code>.
+      </p>
+
+      <details>
+        <summary className="cursor-pointer text-sm text-neutral-500 dark:text-neutral-400 hover:text-neutral-700 dark:hover:text-neutral-300">
+          Alternative: inline data attributes (may not work in all GTM setups)
+        </summary>
+        <CodeBlock filename="GTM → Custom HTML Tag (alternative)">{`<script
   defer
   data-domain="your-site.com"
   src="https://pulse.ciphera.net/script.js"
 ></script>`}</CodeBlock>
+      </details>
 
       <p>
         For more details, see the{' '}