Add EHSAN favicon and localized browser tab titles (Task #21)

The browser tab previously showed a generic placeholder favicon and the
English title "EHSAN Closed Donation Loop". Per the reference, the tab now
shows the EHSAN logo mark and an Arabic platform title.

Changes:
- Favicon: copied the existing EHSAN logo (src/assets/ehsan-logo.png) to
  public/favicon.png and pointed index.html at %BASE_URL%favicon.png
  (base-path safe; verified it serves 200 image/png).
- Static head: index.html <title> and OG/Twitter titles + description now
  use the Arabic platform name "منصة إحسان".
- Per-page titles: added a DocumentTitle component
  (src/hooks/useDocumentTitle.ts) rendered in the Router that sets
  document.title to "<page name> - <platform>" based on the current wouter
  path and active language, reading from a new translations.meta section
  (AR + EN). Home reads "الصفحة الرئيسية - منصة إحسان"; switches with language.

Approach note: titles are centralized in the router rather than edited into
each page file, keeping it DRY while covering all main routes.

Verified: tsc clean; e2e confirmed titles on /, /opportunities, /cart and
English fallback ("Home - EHSAN Platform"), plus favicon load.

artifacts/ehsan-poc/src/lib/i18n/translations.ts

@@ -1,4 +1,20 @@
 export const en = {
+  meta: {
+    platform: "EHSAN Platform",
+    home: "Home",
+    opportunities: "Donation Opportunities",
+    cart: "Your Donation Cart",
+    about: "About EHSAN",
+    track: "Track Case",
+    donate: "Complete Donation",
+    request: "Request Support",
+    waqf: "Endowment",
+    baraem: "EHSAN Buds",
+    admin: "Admin Dashboard",
+    whatsappLog: "WhatsApp Log",
+    thankYou: "Submit Thank You",
+    login: "Login",
+  },
   common: {
     ehsan: "EHSAN",
     home: "Home",
@@ -400,6 +416,22 @@ export const en = {
 };
 
 export const ar = {
+  meta: {
+    platform: "منصة إحسان",
+    home: "الصفحة الرئيسية",
+    opportunities: "فرص التبرع",
+    cart: "سلة تبرعاتك",
+    about: "عن إحسان",
+    track: "تتبع الحالة",
+    donate: "إتمام التبرع",
+    request: "طلب دعم",
+    waqf: "الوقف",
+    baraem: "براعم إحسان",
+    admin: "لوحة الإدارة",
+    whatsappLog: "سجل واتساب",
+    thankYou: "إرسال شكر",
+    login: "تسجيل الدخول",
+  },
   common: {
     ehsan: "إحسان",
     home: "الرئيسية",