style: unify keyboard shortcut hints across tools using Pastel style

- Add shortcut hints below tool descriptions in Figlet and Units pages
- Revert experimental button-based shortcut layout in Units
- Remove redundant shortcut hints from Units footer
- Ensure consistent kbd tag styling across the application

components/units/ui/Footer.tsx

@@ -65,24 +65,6 @@ export default function Footer() {
                 </a>
               </li>
             </ul>
-
-            {/* Keyboard Shortcuts */}
-            <div className="mt-4">
-              <h4 className="font-semibold text-sm mb-2">Keyboard Shortcuts</h4>
-              <ul className="space-y-1 text-xs text-muted-foreground">
-                <li>
-                  <kbd className="px-1.5 py-0.5 bg-muted rounded">/</kbd> Focus search
-                </li>
-                <li>
-                  <kbd className="px-1.5 py-0.5 bg-muted rounded">Ctrl</kbd>
-                  {' + '}
-                  <kbd className="px-1.5 py-0.5 bg-muted rounded">K</kbd> Command palette
-                </li>
-                <li>
-                  <kbd className="px-1.5 py-0.5 bg-muted rounded">ESC</kbd> Close dialogs
-                </li>
-              </ul>
-            </div>
           </div>
         </div>