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/components/MobileCallBar.js

@@ -7,14 +7,14 @@ export default function MobileCallBar() {
     <div className="fixed inset-x-0 bottom-0 z-50 grid grid-cols-2 border-t bg-white md:hidden">
       <a
         href={links.tel}
-        className="flex items-center justify-center gap-2 bg-sky-800 py-3 font-bold text-white"
+        className="flex items-center justify-center gap-2 bg-primary py-3 font-semibold text-primary-foreground"
       >
         <Phone aria-hidden="true" className="size-4" />
         Call
       </a>
       <a
         href={links.sms}
-        className="flex items-center justify-center gap-2 py-3 font-bold text-sky-800"
+        className="flex items-center justify-center gap-2 py-3 font-semibold text-primary"
       >
         <MessageSquare aria-hidden="true" className="size-4" />
         Text