feat: implement PDF attachment editing functionality with web worker support

- Added a new worker script to handle editing of embedded attachments in PDF files.
- Created TypeScript definitions for message structures and response types related to attachment editing.
- Updated the main logic to utilize the worker for improved performance and responsiveness during attachment management.
- Integrated the editing feature into the UI, allowing users to view, remove, or replace attachments in their PDFs.
- Enhanced error handling and user feedback during the editing process.

public/workers/edit-attachments.worker.d.ts

@@ -0,0 +1,42 @@
+declare const coherentpdf: typeof import('../../src/types/coherentpdf.global').coherentpdf;
+
+interface GetAttachmentsMessage {
+  command: 'get-attachments';
+  fileBuffer: ArrayBuffer;
+  fileName: string;
+}
+
+interface EditAttachmentsMessage {
+  command: 'edit-attachments';
+  fileBuffer: ArrayBuffer;
+  fileName: string;
+  attachmentsToRemove: number[];
+}
+
+type EditAttachmentsWorkerMessage = GetAttachmentsMessage | EditAttachmentsMessage;
+
+interface GetAttachmentsSuccessResponse {
+  status: 'success';
+  attachments: Array<{ index: number; name: string; page: number; data: ArrayBuffer }>;
+  fileName: string;
+}
+
+interface GetAttachmentsErrorResponse {
+  status: 'error';
+  message: string;
+}
+
+interface EditAttachmentsSuccessResponse {
+  status: 'success';
+  modifiedPDF: ArrayBuffer;
+  fileName: string;
+}
+
+interface EditAttachmentsErrorResponse {
+  status: 'error';
+  message: string;
+}
+
+type GetAttachmentsResponse = GetAttachmentsSuccessResponse | GetAttachmentsErrorResponse;
+type EditAttachmentsResponse = EditAttachmentsSuccessResponse | EditAttachmentsErrorResponse;
+type EditAttachmentsWorkerResponse = GetAttachmentsResponse | EditAttachmentsResponse;