refactor(sidebar): remove unused store

src/providers/root-providers.tsx

@@ -4,7 +4,7 @@
  * 根级 Client Providers 包装
  *
  * 把所有功能 Provider 串起来：
- *   AuthProvider → UserProvider → SidebarProvider → ChatProvider
+ *   AuthProvider → UserProvider → PaymentProvider → ChatProvider
  *   + AuthStatusChecker（启动时一次：派发 AuthInit）
  *   + OAuthSessionSync   （持续监听 NextAuth session → auth machine）
  *   + UserAuthSync       （auth 登录态恢复后 hydrate user machine）
@@ -22,7 +22,6 @@ import { OAuthSessionSync } from "@/stores/auth/oauth-session-sync";
 import { ChatAuthSync } from "@/stores/chat/chat-auth-sync";
 import { ChatProvider } from "@/stores/chat/chat-context";
 import { PaymentProvider, PaymentSuccessSync } from "@/stores/payment";
-import { SidebarProvider } from "@/stores/sidebar/sidebar-context";
 import { UserAuthSync } from "@/stores/user/user-auth-sync";
 import { UserProvider } from "@/stores/user/user-context";
 
@@ -41,14 +40,12 @@ export function RootProviders({ children }: RootProvidersProps) {
       <UserProvider>
         <UserAuthSync />
         <PaymentProvider>
-          <SidebarProvider>
-            <ChatProvider>
-              <ChatAuthSync />
-              <PaymentSuccessSync />
-              {children}
-              <div id="toast-portal" />
-            </ChatProvider>
-          </SidebarProvider>
+          <ChatProvider>
+            <ChatAuthSync />
+            <PaymentSuccessSync />
+            {children}
+            <div id="toast-portal" />
+          </ChatProvider>
         </PaymentProvider>
       </UserProvider>
     </AuthProvider>