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/main.ts

@@ -138,7 +138,7 @@ const init = () => {
     categoryGroup.className = 'category-group col-span-full';
 
     const title = document.createElement('h2');
-    title.className = 'text-xl font-bold text-indigo-400 mb-4 mt-8 first:mt-0';
+    title.className = 'text-xl font-bold text-indigo-400 mb-4 mt-8 first:mt-0 text-white';
     title.textContent = category.name;
 
     const toolsContainer = document.createElement('div');