feat: journal dashboard widgets, agent polish, and edit-mode live previews

Journal dashboard widgets and quick-add; rich-text quick-add dialogs.

Dashboard draft sync for live edit previews; assistant bubble + API tools.

Journal UX: stress slider, mood grid, query cap fix.

src/app/settings/assistant-actions.ts

@@ -0,0 +1,14 @@
+"use server";
+
+import { eq } from "drizzle-orm";
+import { revalidatePath } from "next/cache";
+import { db } from "@/lib/db";
+import { users } from "@/modules/_core/schema";
+import { getCurrentSession } from "@/lib/session";
+
+export async function setAssistantEnabled(enabled: boolean): Promise<void> {
+  const { user } = await getCurrentSession();
+  await db.update(users).set({ assistantEnabled: enabled }).where(eq(users.id, user.id));
+  revalidatePath("/settings");
+  revalidatePath("/", "layout");
+}