Polish: aria-pressed toggles, deferred row styling, override hint

Fund visibility toggles and the header privacy/theme buttons expose
aria-pressed (FE-16); deferred transactions render struck-through and
muted so the state is visible at a glance (UX-05); the balance-override
input documents its keyboard contract (UX-21). The Budget CSV button
rides in the transactions tab header.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/pages/Pensions.tsx

@@ -523,6 +523,7 @@ export default function Pensions() {
                   <button
                     key={key}
                     onClick={() => toggleFund(key)}
+                    aria-pressed={active}
                     className="flex items-center gap-1.5 px-3 py-1.5 rounded-full text-xs font-medium transition-all border cursor-pointer focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
                     style={{
                       borderColor: fund.color,