polish(ui): loading feedback on sync/refresh buttons system-wide (#1156)

The "Synka bank nu" row in the transactions Importera split button fired
syncAll() with zero visual feedback. SplitButton now takes busy/busyLabel
per option: the primary face and the menu row swap to a spinning Loader2,
show the busy label and go inert until the action resolves. useBankSync
holds isBusy across the whole syncAll loop so the spinner does not
flicker between per-connection syncs.

Sweep of the rest of the system for async buttons missing the same
feedback (convention: disabled + Loader2 animate-spin + label swap):

- bokslut DigitalInlamning "Uppdatera status" (Bolagsverket poll): had no
  feedback at all; now disabled + spinner + "Uppdaterar ..." while polling
- Stripe settings "Synka nu": had disabled + label swap but a static icon
- Skatteverket "Verifiera": had disabled + label swap but no spinner
- AgentMemoryPanel "Dolj"/"Aterstall" row actions: static icons on async
  patch; now swap to spinner for the busy row

Checked and intentionally unchanged: Arcim migration "Synka igen" and
"Ateranslut" (the whole step flips to a spinner view synchronously on
click), skattekonto "Forsok igen" (page flips to loading view), AgentChat
"Generera om" (streaming indicator is the feedback).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/transactions/TransactionStatusBar.tsx

@@ -26,7 +26,7 @@ export default function TransactionStatusBar({
   const t = useTranslations('transactions')
   const router = useRouter()
   const { uiState, loaded } = useUiState()
-  const { connections, hasBankSync, syncAll, lastSyncedAt } = useBankSync()
+  const { connections, hasBankSync, syncAll, lastSyncedAt, isBusy } = useBankSync()
   const formatAge = useAgeFormatter()
 
   // "Synka bank nu" (concept: first menu row) only renders once a bank is
@@ -41,6 +41,8 @@ export default function TransactionStatusBar({
             key: 'synka',
             label: t('create_synka'),
             icon: RefreshCw,
+            busy: isBusy,
+            busyLabel: t('bank_sync_button_syncing'),
             description: lastSyncedAt
               ? t('create_synka_desc_last', { age: formatAge(lastSyncedAt) })
               : t('create_synka_desc'),