Remove Apple SSO, keep Google + GitHub only

- Removed Apple from OAuth lib (config, exchange, provider type)
- Removed Apple button from auth page
- Removed Apple tab from setup guide page
- Removed Apple env vars from .env, .env.example, docker-compose.yml
- Removed Apple prompts from setup-sso.sh

src/app/auth/page.tsx

@@ -32,15 +32,6 @@ function GoogleLogo({ className }: { className?: string }) {
   );
 }
 
-/** Inline Apple SVG logo */
-function AppleLogo({ className }: { className?: string }) {
-  return (
-    <svg className={className} viewBox="0 0 24 24" fill="currentColor">
-      <path d="M17.05 20.28c-.98.95-2.05.88-3.08.4-1.09-.5-2.08-.48-3.24 0-1.44.62-2.2.44-3.06-.4C2.79 15.25 3.51 7.59 9.05 7.31c1.35.07 2.29.74 3.08.8 1.18-.24 2.31-.93 3.57-.84 1.51.12 2.65.72 3.4 1.8-3.12 1.87-2.38 5.98.48 7.13-.57 1.5-1.31 2.99-2.54 4.09zM12.03 7.25c-.15-2.23 1.66-4.07 3.74-4.25.29 2.58-2.34 4.5-3.74 4.25z" />
-    </svg>
-  );
-}
-
 /** Inline GitHub SVG logo */
 function GitHubLogo({ className }: { className?: string }) {
   return (
@@ -141,18 +132,6 @@ export default function AuthPage() {
               </span>
             </button>
 
-            {/* Apple */}
-            <button
-              onClick={() => handleProviderClick("apple")}
-              disabled={authLoading}
-              className="w-full flex items-center gap-4 px-5 py-4 rounded-2xl bg-[#111118] border border-gray-800/60 active:bg-[#1a1a24] disabled:opacity-50 transition-all touch-manipulation"
-            >
-              <AppleLogo className="w-6 h-6 shrink-0 text-white" />
-              <span className="text-sm font-medium text-white">
-                Continue with Apple
-              </span>
-            </button>
-
             {/* GitHub */}
             <button
               onClick={() => handleProviderClick("github")}