add .github/copilot-instructions.md file

https://docs.github.com/en/copilot/customizing-copilot/adding-repository-custom-instructions-for-github-copilot

components/layout/theme-toggle.tsx

@@ -12,11 +12,12 @@ const ThemeToggle = ({ ...rest }: ComponentPropsWithoutRef<LucideIcon>) => {
   return (
     <button
       onClick={() => setTheme(theme === "light" ? "dark" : "light")}
-      aria-label="Toggle Theme"
+      aria-label="Toggle theme"
       className="hover:*:stroke-warning block bg-transparent p-2.5 hover:cursor-pointer not-dark:[&_.lucide-moon]:hidden dark:[&_.lucide-sun]:hidden"
     >
-      <SunIcon aria-label="Light Mode" {...rest} />
-      <MoonIcon aria-label="Dark Mode" {...rest} />
+      <SunIcon {...rest} />
+      <MoonIcon {...rest} />
+      <span className="sr-only">Toggle theme</span>
     </button>
   );
 };