Add about/contact/installments pages, fix category slot bugs, wire live branding

- Enlarge category carousel thumbnails (90px -> 104-140px responsive) and
  confirm the slider/categories/banner static-image slots are all reading
  correctly from the CMS (verified live, not a wiring bug)
- Fix installments page dropping "هندزفری و هدفون": it's a level-3 category,
  not level-2, so level2.find() silently missed it - use findNode() over the
  whole tree instead
- Extend gen-category-placeholders.mjs to generate a placeholder for every
  category at every level (was level-2 only), needed for the fix above
- Add /about, /contact, /installments pages
  - About: real copy transcribed from the live moalem.shop theme, real
    product photos from the API, text-only brand strip (no scraped logos)
  - Contact: ContactForm.tsx posts to the real POST /contact-submissions,
    branch cards with key-less Google Maps embeds
  - Installments: flat brand-colored hero (no photo/gradient), category
    highlights reusing the same categories slot images as the homepage
- Replace the placeholder header/footer phone number with the real one, add
  real branch addresses and Instagram/Telegram links (src/data/site.ts),
  pulled from the live theme's footer
- Wire logo/favicon to GET /website/favicon (getFavicon() in api.ts) instead
  of the static bundled files, so a dashboard upload now shows automatically;
  layout.tsx metadata is now generateMetadata() to support this. The tenant's
  uploaded logo/favicon currently belongs to a different business - the
  wiring is correct and will self-correct once that's fixed in the dashboard

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/components/ui/TrustBadges.tsx

@@ -0,0 +1,26 @@
+import type { ComponentType } from "react";
+
+export interface TrustBadge {
+  icon: ComponentType<{ className?: string }>;
+  title: string;
+  desc: string;
+}
+
+// Shared trust-point row used on /about and /installments — same visual
+// language as the badges in ProductBuyPanel, just laid out wider.
+export default function TrustBadges({ items }: { items: TrustBadge[] }) {
+  return (
+    <div className="grid grid-cols-2 gap-6 sm:grid-cols-3 lg:grid-cols-5">
+      {items.map((item) => (
+        <div
+          key={item.title}
+          className="flex flex-col items-center gap-2 rounded-xl border border-line bg-white p-5 text-center"
+        >
+          <item.icon className="size-7 text-brand" />
+          <span className="text-[13px] font-bold text-ink">{item.title}</span>
+          <span className="text-[11.5px] leading-5 text-body">{item.desc}</span>
+        </div>
+      ))}
+    </div>
+  );
+}