feat: add brand imagery to documentation and demo app

- Added banner image to README.md for improved project presentation
- Integrated Crest logo into demo app navbar alongside brand text
- Added required image assets to .github/assets and public directories
- Updated navbar brand link to use flex layout for logo alignment

Author: Erics1337

.github/assets/crest-ui-banner.png

@@ -1,5 +1,5 @@
 # 🏔️ Crest UI — Design System
-
+![Crest UI — Design System & UI Framework](.github/assets/crest-ui-banner.png)
 A design-forward, component-driven UI system that blends modern SaaS clarity with the textures and palette of the high desert and mountains. Built for speed, polish, and multi-brand extensibility across Crest Code Creative projects.
 
 - **Framework**: React + Next.js

README.md

@@ -1,6 +1,7 @@
 import type { Metadata } from "next";
 import "./globals.css";
 import Link from "next/link";
+import Image from "next/image";
 import { Navbar, NavbarInner, NavbarBrand, NavbarNav, NavbarItem, Footer, FooterInner, FooterNote } from "@crest-ui/ui/server";
 
 export const metadata: Metadata = {
@@ -15,7 +16,10 @@ export default function RootLayout({ children }: { children: React.ReactNode })
         <Navbar elevated>
           <NavbarInner>
             <NavbarBrand>
-              <Link href="/" className="hover:opacity-80">Crest</Link>
+              <Link href="/" className="flex items-center gap-2 hover:opacity-80">
+                <Image src="/crest-logo.png" alt="Crest Code Creative logo" width={28} height={28} priority />
+                <span>Crest</span>
+              </Link>
             </NavbarBrand>
             <NavbarNav>
               <NavbarItem>