feat: enhance PDF tools with new features and UI improvements

- Added 'Extract Attachments' and 'Edit Attachments' functionalities to manage embedded files in PDFs.
- Introduced new splitting options: by bookmarks and by a specified number of pages (N times).
- Updated the user interface to include new options and improved layout for better usability.
- Enhanced the GitHub link display with dynamic star count retrieval.
- Bumped version to 1.4.0 and updated footer to reflect the new version.
- Refactored existing code for better maintainability and added new TypeScript definitions for the new features.

src/js/utils/cpdf-helper.ts

@@ -0,0 +1,42 @@
+let cpdfLoaded = false;
+let cpdfLoadPromise: Promise<void> | null = null;
+
+//TODO: @ALAM,is it better to use a worker to load the cpdf library?
+// or just use the browser version?
+export async function ensureCpdfLoaded(): Promise<void> {
+  if (cpdfLoaded) return;
+
+  if (cpdfLoadPromise) {
+    return cpdfLoadPromise;
+  }
+
+  cpdfLoadPromise = new Promise((resolve, reject) => {
+    if (typeof (window as any).coherentpdf !== 'undefined') {
+      cpdfLoaded = true;
+      resolve();
+      return;
+    }
+
+    const script = document.createElement('script');
+    script.src = '/coherentpdf.browser.min.js';
+    script.onload = () => {
+      cpdfLoaded = true;
+      resolve();
+    };
+    script.onerror = () => {
+      reject(new Error('Failed to load CoherentPDF library'));
+    };
+    document.head.appendChild(script);
+  });
+
+  return cpdfLoadPromise;
+}
+
+/**
+ * Gets the cpdf instance, ensuring it's loaded first
+ */
+export async function getCpdf(): Promise<any> {
+  await ensureCpdfLoaded();
+  return (window as any).coherentpdf;
+}
+