feat: use "mode" instead of "thinking_enabled" and "is_plan_mode"

frontend/src/app/workspace/chats/[thread_id]/page.tsx

@@ -108,7 +108,11 @@ export default function ChatPage() {
     isNewThread,
     threadId,
     thread,
-    threadContext: settings.context,
+    threadContext: {
+      ...settings.context,
+      thinking_enabled: settings.context.mode !== "flash",
+      is_plan_mode: settings.context.mode === "pro",
+    },
     afterSubmit() {
       router.push(pathOfThread(threadId!));
     },

frontend/src/app/workspace/layout.tsx

@@ -5,7 +5,6 @@ import { useCallback, useEffect, useState } from "react";
 import { Toaster } from "sonner";
 
 import { SidebarInset, SidebarProvider } from "@/components/ui/sidebar";
-import { Overscroll } from "@/components/workspace/overscroll";
 import { WorkspaceSidebar } from "@/components/workspace/workspace-sidebar";
 import { useLocalSettings } from "@/core/settings";