feat(signature): add font and color customization for typed signatures

feat(stamps): implement new add stamps tool with image stamp support

fix(form-filler): improve form filler UI and XFA form support

refactor(sign-pdf): improve signature tool initialization and error handling

style(ui): update text color for better visibility in dark mode

chore: update navigation links to use root-relative paths

src/js/config/tools.ts

@@ -137,6 +137,12 @@ export const categories = [
         icon: 'pen-tool',
         subtitle: 'Draw, type, or upload your signature.',
       },
+      {
+        href: '/src/pages/add-stamps.html',
+        name: 'Add Stamps',
+        icon: 'stamp',
+        subtitle: 'Add image stamps to your PDF using the annotation toolbar.',
+      },
       {
         id: 'remove-annotations',
         name: 'Remove Annotations',
@@ -153,7 +159,7 @@ export const categories = [
         id: 'form-filler',
         name: 'PDF Form Filler',
         icon: 'square-pen',
-        subtitle: 'Fill in forms directly in the browser.',
+        subtitle: 'Fill in forms directly in the browser. Also supports XFA forms.',
       },
       {
         id: 'remove-blank-pages',