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/lib/api.ts

@@ -4,6 +4,7 @@ import type {
   ApiCategory,
   ApiProduct,
   AuthUser,
+  BrandAssets,
   BusinessInfo,
   ContactFormInput,
   EntityComment,
@@ -86,6 +87,13 @@ export function getBusinessInfo(): Promise<BusinessInfo> {
   return apiGet<BusinessInfo>(t("/website/business-info"));
 }
 
+// Single documented source for header/footer logos and the browser-tab
+// icon — see AGENTS.md "Branding". Prefer this over reading logoUrl off
+// getTenant()/getBusinessInfo() directly.
+export function getFavicon(): Promise<BrandAssets> {
+  return apiGet<BrandAssets>(t("/website/favicon"));
+}
+
 export function getSliders(): Promise<SliderItem[]> {
   return apiGet<{ items: SliderItem[] }>(t("/website/sliders")).then((r) => r.items);
 }

src/lib/types.ts

@@ -23,6 +23,16 @@ export interface Tenant {
   faviconUrl: string | null;
 }
 
+// GET /tenants/{domain}/website/favicon — the documented single source for
+// header/footer logos and the browser-tab icon (falls back to the light
+// logo when hasDedicatedFavicon is false).
+export interface BrandAssets {
+  faviconUrl: string | null;
+  logoUrl: string | null;
+  logoDarkUrl: string | null;
+  hasDedicatedFavicon: boolean;
+}
+
 // This tenant has no emails/phones/addresses filled in yet, so the loose
 // shapes are read defensively at render time.
 export interface BusinessInfo {