feat: restore direct PDF download via background; drop printdoc

content.js

@@ -150,25 +150,17 @@
     const btn = document.getElementById(BTN_ID);
     try {
       btn.disabled = true;
-      btn.innerHTML = '<i class="fa fa-spinner fa-spin"></i> Opening...';
+      btn.innerHTML = '<i class="fa fa-spinner fa-spin"></i> Downloading...';
       const { header, courses } = await scrapeStudyLoad();
       const included = ISMIStools.filterStudyLoadCourses(courses);
       if (!included.length) throw new Error('No enrolled courses found.');
       const totalUnits = ISMIStools.sumUnits(included);
-      const html = ISMIStools.buildStudyLoadHtml({ header, courses: included, totalUnits });
-      const blob = new Blob([html], { type: 'text/html' });
-      const url = URL.createObjectURL(blob);
-      const win = window.open(url, '_blank');
-      if (!win) {
-        URL.revokeObjectURL(url);
-        showToast('Popup blocked — allow popups for this site, then try again.', true);
-        return;
-      }
-      // The blob document runs its own onload → window.print(). Never touch
-      // win.document here: if the new tab navigates cross-origin, accessing it
-      // throws "Permission denied".
-      setTimeout(() => URL.revokeObjectURL(url), 60000);
-      showToast('Opened printable Study Load.');
+      const res = await browser.runtime.sendMessage({
+        type: 'generate-pdf',
+        data: { header, courses: included, totalUnits }
+      });
+      if (!res || !res.ok) throw new Error((res && res.error) || 'PDF generation failed');
+      showToast('PDF downloaded.');
     } catch (err) {
       showToast('Error: ' + ((err && err.message) || err), true);
     } finally {