feat(ui): storage, map, search, wintering and statistics without dead ends

- Every query shows loading, an error with "Erneut versuchen", an empty
  state with a next step, then data; statistics no longer hang on
  "Lädt…" after an error, a failed search no longer reads as "no hits".
- Storage: one primary action, stock items as a clearly secondary
  section, low stock as icon + word.
- Wintering: "Gassen" explained, outcome as icon + word, touch-size
  edit buttons; map: tells how many apiaries have coordinates.
- Statistics: units and plain words instead of "Ø", a select instead
  of crowded tabs on phones.
- QR code buttons are touch size.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Frontend/src/components/qr-code-dialog.tsx

@@ -56,7 +56,7 @@ export function QrCodeDialog({ entityType, id, label = "QR-Code" }: QrCodeDialog
     <Dialog open={open} onOpenChange={setOpen}>
       <DialogTrigger
         render={
-          <Button variant="outline" size="sm">
+          <Button variant="outline" size="touch">
             <QrCode className="size-4" />
             {label}
           </Button>
@@ -79,7 +79,7 @@ export function QrCodeDialog({ entityType, id, label = "QR-Code" }: QrCodeDialog
         {nfcSupported ? (
           <Button
             variant="outline"
-            size="sm"
+            size="touch"
             onClick={() => void handleWriteNfc()}
             disabled={isWritingNfc}
           >