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/logic/extract-attachments.ts

@@ -0,0 +1,86 @@
+import { showLoader, hideLoader, showAlert } from '../ui.js';
+import { downloadFile, readFileAsArrayBuffer } from '../utils/helpers.js';
+import { state } from '../state.js';
+import { PDFDocument as PDFLibDocument } from 'pdf-lib';
+import JSZip from 'jszip';
+
+export async function extractAttachments() {
+  if (state.files.length === 0) {
+    showAlert('No Files', 'Please select at least one PDF file.');
+    return;
+  }
+
+  showLoader('Extracting attachments...');
+  try {
+    const zip = new JSZip();
+    let totalAttachments = 0;
+
+    for (const file of state.files) {
+      const pdfBytes = await readFileAsArrayBuffer(file);
+      const pdfDoc = await PDFLibDocument.load(pdfBytes as ArrayBuffer, {
+        ignoreEncryption: true,
+      });
+
+      const embeddedFiles = pdfDoc.context.enumerateIndirectObjects()
+        .filter(([ref, obj]: any) => {
+          // obj must be a PDFDict
+          if (obj && typeof obj.get === 'function') {
+            const type = obj.get('Type');
+            return type && type.toString() === '/Filespec';
+          }
+          return false;
+        });
+
+      if (embeddedFiles.length === 0) {
+        console.warn(`No attachments found in ${file.name}`);
+        continue;
+      }
+
+      // Extract attachments
+      const baseName = file.name.replace(/\.pdf$/i, '');
+      for (let i = 0; i < embeddedFiles.length; i++) {
+        try {
+          const [ref, fileSpec] = embeddedFiles[i];
+          const fileSpecDict = fileSpec as any;
+          
+          // Get attachment name
+          const fileName = fileSpecDict.get('UF')?.decodeText() || 
+                         fileSpecDict.get('F')?.decodeText() || 
+                         `attachment-${i + 1}`;
+          
+          // Get embedded file stream
+          const ef = fileSpecDict.get('EF');
+          if (ef) {
+            const fRef = ef.get('F') || ef.get('UF');
+            if (fRef) {
+              const fileStream = pdfDoc.context.lookup(fRef);
+              if (fileStream) {
+                const fileData = (fileStream as any).getContents();
+                zip.file(`${baseName}_${fileName}`, fileData);
+                totalAttachments++;
+              }
+            }
+          }
+        } catch (e) {
+          console.warn(`Failed to extract attachment ${i} from ${file.name}:`, e);
+        }
+      }
+    }
+
+    if (totalAttachments === 0) {
+      showAlert('No Attachments', 'No attachments were found in the selected PDF(s).');
+      hideLoader();
+      return;
+    }
+
+    const zipBlob = await zip.generateAsync({ type: 'blob' });
+    downloadFile(zipBlob, 'extracted-attachments.zip');
+    showAlert('Success', `Extracted ${totalAttachments} attachment(s) successfully!`);
+  } catch (e) {
+    console.error(e);
+    showAlert('Error', 'Failed to extract attachments. The PDF may not contain attachments or may be corrupted.');
+  } finally {
+    hideLoader();
+  }
+}
+