fix(seo): apply critical and high-priority SEO fixes

app/(main)/blog/[slug]/page.tsx

@@ -124,7 +124,6 @@ export default async function BlogPostPage({ params }: BlogPostPageProps) {
     articleSection: post.category.name,
     keywords: post.tags.join(", "),
     wordCount,
-    timeRequired: `PT${readingTime}M`,
   };
 
   return (

app/(main)/challenges/[slug]/page.tsx

@@ -51,7 +51,7 @@ export async function generateMetadata({
   const challenge = await getChallengeBySlug(slug);
 
   if (!challenge) {
-    return {};
+    return generateSEOMetadata({ noIndex: true });
   }
 
   const difficultyLabels: Record<string, string> = {

app/(main)/themes/[slug]/page.tsx

@@ -52,7 +52,7 @@ export async function generateMetadata({
   const theme = await getThemeBySlug(slug);
 
   if (!theme) {
-    return {};
+    return generateSEOMetadata({ noIndex: true });
   }
 
   return generateSEOMetadata({

app/layout.tsx

@@ -13,10 +13,19 @@ import {
 } from "@/lib/seo";
 import { TRPCReactProvider } from "@/trpc/client";
 import "./globals.css";
-import { ReactQueryDevtools } from "@tanstack/react-query-devtools";
+import dynamic from "next/dynamic";
 import { Toaster } from "sonner";
 import { Providers } from "@/components/providers";
 
+const ReactQueryDevtools =
+  process.env.NODE_ENV === "development"
+    ? dynamic(() =>
+        import("@tanstack/react-query-devtools").then((m) => ({
+          default: m.ReactQueryDevtools,
+        })),
+      )
+    : () => null;
+
 export const metadata: Metadata = generateMetadata();
 
 export const viewport: Viewport = {

app/login/page.tsx

@@ -1,10 +1,14 @@
+import type { Metadata } from "next";
 import { headers } from "next/headers";
 import Image from "next/image";
 import Link from "next/link";
 import { redirect } from "next/navigation";
 import { Suspense } from "react";
 import { LoginCard } from "@/components/login-card";
 import { auth } from "@/lib/auth";
+import { generateMetadata as generateSEOMetadata } from "@/lib/seo";
+
+export const metadata: Metadata = generateSEOMetadata({ noIndex: true });
 
 interface LoginPageProps {
   searchParams: Promise<{ next?: string }>;