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/settings/AgentMemoryPanel.tsx

@@ -371,7 +371,11 @@ export function AgentMemoryPanel() {
                                   onClick={() => patch(row.id, { is_active: false })}
                                   disabled={isBusy}
                                 >
-                                  <Trash2 className="mr-1 h-3.5 w-3.5" />
+                                  {isBusy ? (
+                                    <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
+                                  ) : (
+                                    <Trash2 className="mr-1 h-3.5 w-3.5" />
+                                  )}
                                   Dölj
                                 </Button>
                               </>
@@ -382,7 +386,11 @@ export function AgentMemoryPanel() {
                                 onClick={() => patch(row.id, { is_active: true })}
                                 disabled={isBusy}
                               >
-                                <RotateCcw className="mr-1 h-3.5 w-3.5" />
+                                {isBusy ? (
+                                  <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
+                                ) : (
+                                  <RotateCcw className="mr-1 h-3.5 w-3.5" />
+                                )}
                                 Återställ
                               </Button>
                             )}