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>

scripts/gen-category-placeholders.mjs

@@ -1,6 +1,9 @@
-// Writes one placeholder thumbnail per top-level product category into
-// public/images/categories/{id}.svg. They are meant to be replaced with real
-// artwork one file at a time — the carousel reads the same paths either way.
+// Writes one placeholder thumbnail per product category (every level, not
+// just level-2) into public/images/categories/{id}.svg. They are meant to be
+// replaced with real artwork one file at a time — the carousel and any other
+// page that links a specific category id (e.g. /installments) read the same
+// paths either way, so every id needs a file, not just the level-2 ones the
+// homepage carousel shows by default.
 // Run: node scripts/gen-category-placeholders.mjs
 import { mkdir, writeFile } from "node:fs/promises";
 
@@ -12,14 +15,17 @@ const res = await fetch(
 );
 const { items } = await res.json();
 
-const roots = items.filter((c) => c.parentId === null).map((c) => c.id);
-const level2 = items.filter((c) => c.parentId && roots.includes(c.parentId));
+// Root categories (parentId === null) have no icon of their own on this
+// site — nothing links directly to "کالای دیجیتال" itself — so only their
+// descendants get a placeholder.
+const roots = new Set(items.filter((c) => c.parentId === null).map((c) => c.id));
+const withIcons = items.filter((c) => !roots.has(c.id));
 
 await mkdir(OUT, { recursive: true });
 
 const escape = (s) => s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
 
-for (const cat of level2) {
+for (const cat of withIcons) {
   const label = escape(cat.nameFa || cat.name);
   const svg = `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 120 120" width="120" height="120" role="img" aria-label="${label}">
   <circle cx="60" cy="60" r="59" fill="#f6f7f9" stroke="#ececec"/>
@@ -31,4 +37,4 @@ for (const cat of level2) {
   await writeFile(new URL(`${cat.id}.svg`, OUT), svg, "utf8");
 }
 
-console.log(`wrote ${level2.length} placeholders to public/images/categories/`);
+console.log(`wrote ${withIcons.length} placeholders to public/images/categories/`);