feat(pdf-tools): add attachments feature to embed files in PDFs

Implement new functionality to allow embedding attachments into PDF documents. The feature includes:
- UI for selecting PDF and files to attach
- Logic to embed files while preserving metadata
- Display of attached files with size information
- Download of modified PDF with embedded files

src/js/config/pdf-tools.ts

@@ -38,6 +38,7 @@ export const singlePdfLoadTools = [
   'form-filler',
   'posterize',
   'remove-blank-pages',
+  'add-attachments',
 ];
 
 export const simpleTools = [

src/js/config/tools.ts

@@ -282,6 +282,12 @@ export const categories = [
         icon: 'files',
         subtitle: 'Duplicate, reorder, and delete pages.',
       },
+      {
+        id: 'add-attachments',
+        name: 'Add Attachments',
+        icon: 'paperclip',
+        subtitle: 'Embed one or more files into your PDF.',
+      },
       {
         id: 'split',
         name: 'Split PDF',
@@ -383,7 +389,7 @@ export const categories = [
         icon: 'ruler-dimension-line',
         subtitle: 'Standardize all pages to a uniform size.',
       },
-      { 
+      {
         id: 'linearize',
         name: 'Linearize PDF',
         icon: 'zap',