feat: add all-accounts portfolio pages

Reuse account sections and group securities with per-account holdings.

Use Mantine Select to preserve filters and reset pagination on scope changes.

Document component reuse guardrails and cover routes, grouping and scope switching.

src/entities/brokerage-event/ui/BrokerageEventCard.tsx

@@ -19,6 +19,7 @@ const BrokerageEventCard: FC<BrokerageEventCardProps> = (props) => {
 		date,
 		event.dateKind === "registry" ? t("events.dateKind.registry") : null,
 		event.isin,
+		event.account?.name,
 	]
 		.filter(Boolean)
 		.join(" · ");