🎨 Palette: Add skip-to-content link for keyboard accessibility (#169)

💡 What: Added a "Skip to content" link that is visually hidden by default but appears when focused via keyboard. Pointed it to the main content area using `id="main-content"` and `tabIndex={-1}`.
🎯 Why: Keyboard users and screen readers must otherwise tab through the entire navigation menu on every page load before reaching the actual page content. This is tedious and a poor UX.
📸 Before/After: Before, keyboard focus started on "Home" in the header. After, the first tab press shows the "Skip to content" link at the top left of the screen.
♿ Accessibility: Massively improves WCAG compliance (Bypass Blocks) and keyboard navigation efficiency.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: ralksta <ralksta@users.noreply.github.com>

app/layout.tsx

@@ -90,6 +90,9 @@ export default function RootLayout({ children }: { children: React.ReactNode })
         <link rel="stylesheet" href={fontsUrl} />
       </head>
       <body>
+        <a href="#main-content" className="skip-link">
+          Skip to content
+        </a>
         <header className="header">
           <nav className="header__nav">
             <Link href="/" className="header__nav-link">
@@ -107,7 +110,9 @@ export default function RootLayout({ children }: { children: React.ReactNode })
             <ThemeToggle />
           </nav>
         </header>
-        <main className="main">{children}</main>
+        <main id="main-content" tabIndex={-1} className="main">
+          {children}
+        </main>
         <Footer />
         <ScrollToTop />
         {process.env.NODE_ENV === 'development' && <DevToolbarLoader />}