fix(logo): embed logo as base64 to fix Vercel LFS issue

Vercel does not download Git LFS objects during build, so logo.png
was served as a text pointer file. Embedding the logo as a base64
data URI in lib/logo.ts eliminates the LFS dependency entirely and
ensures the logo loads correctly on all platforms (Vercel, local).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/components/footer.tsx

@@ -1,8 +1,8 @@
 "use client"
 
 import { motion } from "framer-motion"
-import Image from "next/image"
 import Link from "next/link"
+import { LOGO_SRC } from "@/lib/logo"
 
 export function Footer() {
   return (
@@ -22,7 +22,7 @@ export function Footer() {
             className="md:col-span-2"
           >
             <Link href="/" className="flex items-center gap-3 mb-4">
-              <Image src="/logo.png" alt="تبيان" width={52} height={52} className="object-contain drop-shadow-md" />
+              <img src={LOGO_SRC} alt="تبيان" width={52} height={52} className="object-contain drop-shadow-md" />
               <span className="text-2xl font-bold text-foreground">تبيان</span>
             </Link>
             <p className="text-muted-foreground leading-relaxed max-w-sm mb-6">

frontend/components/header.tsx

@@ -3,8 +3,8 @@
 import { useState, useEffect } from "react"
 import { motion, AnimatePresence } from "framer-motion"
 import Link from "next/link"
-import Image from "next/image"
 import { useAuth } from "@/lib/auth-context"
+import { LOGO_SRC } from "@/lib/logo"
 import { UserMenu, MobileSignOut } from "@/components/auth/user-menu"
 import { AuthModal } from "@/components/auth/auth-modal"
 
@@ -47,7 +47,7 @@ export function Header({ darkMode, toggleDark }: HeaderProps) {
           {/* Logo */}
           <Link href="/" className="flex items-center gap-3 group">
             <motion.div whileHover={{ scale: 1.05 }} whileTap={{ scale: 0.95 }}>
-              <Image src="/logo.png" alt="تبيان" width={52} height={52} className="object-contain drop-shadow-md" />
+              <img src={LOGO_SRC} alt="تبيان" width={52} height={52} className="object-contain drop-shadow-md" />
             </motion.div>
             <span className="text-2xl font-bold text-foreground">تبيان</span>
           </Link>