feat: improve mobile responsiveness across UI components

- Add responsive layout for action buttons (stack vertically on mobile, horizontal on sm+)
- Adjust card max-widths for better mobile display (LocationCard, MultiBillEdit)
- Improve button text sizing with responsive classes (text-sm on mobile, text-xs on sm+)
- Remove width constraints on file inputs and info boxes for full-width mobile layout
- Fine-tune icon positioning for better visual alignment

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app/ui/AddLocationButton.tsx

@@ -8,20 +8,21 @@ import { useTranslations } from 'next-intl';
 
 export interface AddLocationButtonProps {
     /** year and month at which the new billing location should be addes */
-    yearMonth: YearMonth
+    yearMonth: YearMonth;
+    className?: string;
 }
 
-export const AddLocationButton:React.FC<AddLocationButtonProps> = ({yearMonth}) => {
+export const AddLocationButton:React.FC<AddLocationButtonProps> = ({yearMonth, className}) => {
 
     const t = useTranslations("home-page.add-location-button");
 
     return(
-        <div className="card card-compact card-bordered bg-base-100 shadow-s my-1">
+        <div className={`card card-compact card-bordered bg-base-100 shadow-s my-1 ${className}`}>
             <Link href={`/home/location/${ formatYearMonth(yearMonth) }/add`} className="card-body tooltip self-center" data-tip={t("tooltip")} data-umami-event="add-new-location">
                 <span className='flex self-center'>
-                    <HomeIcon className="h-[1em] w-[1em] cursor-pointer text-4xl" />
-                    <PlusCircleIcon className="h-[1em] w-[1em] cursor-pointer text-xl text-green-500 ml-[-.6em] mt-[-.4em]"  />
-                    <span className="ml-1 self-center text-xs text-left leading-[1.2em] w-[5.5em]">{t("tooltip")}</span>
+                    <HomeIcon className="h-[1em] w-[1em] cursor-pointer text-4xl mt-[.1rem]" />
+                    <PlusCircleIcon className="h-[1em] w-[1em] cursor-pointer text-xl text-green-500 ml-[-.6em] mt-[-.3em]"  />
+                    <span className="ml-1 self-center text-sm sm:text-xs text-left w-[5.5em] leading-[1.3em]">{t("tooltip")}</span>
                 </span>
             </Link>
         </div>