Swap to shadcn components and polish the design

Components (added via the shadcn MCP/CLI):
- Navbar: NavigationMenu on desktop, Sheet on mobile; drops
  Navbar.module.css and the hand-rolled slide-down menu
- Buttons: shadcn Button via a shared ContactButtons component
  (replaces Button.js and its CSS module)
- Card for price cards, testimonials, the business block and plan;
  Table for prices; Input/Textarea/Label/NativeSelect/RadioGroup and
  Alert in the quote form; Separator in the footer
- Components import cn from @/lib/utils (not the new "cn" package);
  accordion moved to the unified radix-ui package

Design tweaks:
- Geist Sans is actually applied (font variables were on <body>, but
  Tailwind reads them on <html>, so the site fell back to system fonts)
- Theme primary set to the existing brand blue; slightly smaller radius
- Balanced, tighter heading tracking; muted secondary text
- 44px contact buttons; 16px FAQ text; tighter homepage spacing
- Full-width selects with 16px text on phones (no iOS zoom)

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/windows-10/page.js

@@ -1,10 +1,9 @@
 import Link from "next/link";
-import { MessageSquare, Phone } from "lucide-react";
 import HeaderSm from "../components/HeaderSm";
-import Button from "../components/Button";
+import ContactButtons from "../components/ContactButtons";
 import CtaBand from "../components/CtaBand";
 import FaqList from "../components/FaqList";
-import { business, links, pageMetadata } from "@/lib/site";
+import { pageMetadata } from "@/lib/site";
 
 export const metadata = pageMetadata({
   title: "Still on Windows 10? What to Do Now | Te Atatu Computers",
@@ -62,16 +61,7 @@ export default function Windows10Page() {
           buy a new computer. Here are your options, and I'm happy to
           check which one suits you for free.
         </p>
-        <div className="flex flex-col sm:flex-row gap-3">
-          <Button href={links.tel} variant="primary">
-            <Phone aria-hidden="true" />
-            Call {business.phone}
-          </Button>
-          <Button href={links.sms} variant="outlineDark">
-            <MessageSquare aria-hidden="true" />
-            Text for a free check
-          </Button>
-        </div>
+        <ContactButtons textLabel="Text for a free check" />
       </section>
 
       <section className="container mx-auto max-w-3xl mb-16">
@@ -79,7 +69,7 @@ export default function Windows10Page() {
         <ol className="space-y-6">
           {options.map(({ title, text }, i) => (
             <li key={title} className="flex gap-4">
-              <span className="flex size-10 shrink-0 items-center justify-center rounded-full bg-sky-800 font-bold text-white">
+              <span className="flex size-10 shrink-0 items-center justify-center rounded-full bg-primary font-bold text-white">
                 {i + 1}
               </span>
               <div>
@@ -92,7 +82,7 @@ export default function Windows10Page() {
         <p className="mt-6">
           Not sure? Get in touch and I&apos;ll give you a straight answer. See
           all prices on the{" "}
-          <Link href="/pricing" className="text-sky-800 underline">
+          <Link href="/pricing" className="text-primary underline">
             pricing page
           </Link>
           .