feat: refactor announcements page and layout to support sidebar slide-out functionality

- Replaced the existing announcement card and empty state components with imports from the new announcements directory.
- Introduced state management for the announcements sidebar in the LayoutDataProvider.
- Updated navigation items to handle announcements sidebar toggling.
- Integrated AnnouncementsSidebar into the LayoutShell for both mobile and desktop views.
- Enhanced sidebar handling to improve user experience when navigating announcements.

surfsense_web/components/layout/ui/shell/LayoutShell.tsx

@@ -13,6 +13,7 @@ import { IconRail } from "../icon-rail";
 import {
 	AllPrivateChatsSidebar,
 	AllSharedChatsSidebar,
+	AnnouncementsSidebar,
 	InboxSidebar,
 	MobileSidebar,
 	MobileSidebarTrigger,
@@ -82,6 +83,10 @@ interface LayoutShellProps {
 	className?: string;
 	// Inbox props
 	inbox?: InboxProps;
+	announcementsPanel?: {
+		open: boolean;
+		onOpenChange: (open: boolean) => void;
+	};
 	isLoadingChats?: boolean;
 	// All chats panel props
 	allSharedChatsPanel?: {
@@ -130,6 +135,7 @@ export function LayoutShell({
 	children,
 	className,
 	inbox,
+	announcementsPanel,
 	isLoadingChats = false,
 	allSharedChatsPanel,
 	allPrivateChatsPanel,
@@ -211,6 +217,15 @@ export function LayoutShell({
 							/>
 						)}
 
+						{/* Mobile Announcements Sidebar - only render when open to avoid scroll blocking */}
+						{announcementsPanel?.open && (
+							<AnnouncementsSidebar
+								open={announcementsPanel.open}
+								onOpenChange={announcementsPanel.onOpenChange}
+								onCloseMobileSidebar={() => setMobileMenuOpen(false)}
+							/>
+						)}
+
 						{/* Mobile All Shared Chats - slide-out panel */}
 						{allSharedChatsPanel && (
 							<AllSharedChatsSidebar
@@ -325,6 +340,14 @@ export function LayoutShell({
 							/>
 						)}
 
+						{/* Announcements Sidebar - positioned absolutely on top of content */}
+						{announcementsPanel && (
+							<AnnouncementsSidebar
+								open={announcementsPanel.open}
+								onOpenChange={announcementsPanel.onOpenChange}
+							/>
+						)}
+
 						{/* All Shared Chats - slide-out panel */}
 						{allSharedChatsPanel && (
 							<AllSharedChatsSidebar