Fix revalidatePath during render in getDefaultDashboardSlug

On a new user's first load, getDefaultDashboardSlug fell through to
createDashboard("Home"), which calls revalidatePath("/"). That is illegal
in a render context (page component → server action → revalidatePath).

Inline the DB insert directly in the fallback and skip revalidatePath —
the redirect that immediately follows is a fresh request, so no cache
invalidation is needed here.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/d/actions.ts

@@ -50,9 +50,13 @@ export async function getDefaultDashboardSlug(): Promise<string> {
     .orderBy(asc(dashboards.position), asc(dashboards.createdAt))
     .limit(1);
   if (first) return first.slug;
-  // No dashboards yet — create Home
+  // No dashboards yet — insert one directly without revalidatePath (we're in a
-  await createDashboard("Home");
+  // render path; the redirect that follows is a fresh request anyway).
-  return "home";
+  const slug = await uniqueSlug(user.id, "home");
+  await db
+    .insert(dashboards)
+    .values({ userId: user.id, name: "Home", slug, isDefault: false, position: 0 });
+  return slug;
 }
 
 export async function getDashboardBySlug(slug: string) {