feat(auth): redesign auth pages with glass UI and motion animations

- error page: replace Card with glass-strong panel, add AlertTriangle icon
- signin page: add framer-motion entrance animation, CalendarDays branding,
  Loader2 spinner while loading, merge isPending/session checks
- signout page: replace Card with glass-strong panel, add LogOut icon,
  tighten user identity display

src/app/auth/error/page.tsx

@@ -1,12 +1,12 @@
 "use client";
 
+import { AlertTriangle } from "lucide-react";
 import Link from "next/link";
 import { useSearchParams } from "next/navigation";
 import { Suspense } from "react";
 import { Button } from "@/components/ui/button";
-import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 
-function Search() {
+function ErrorMessage() {
 	const searchParams = useSearchParams();
 	const errorMessage = searchParams.get("error");
 
@@ -16,7 +16,7 @@ function Search() {
 		: "An authentication error occurred";
 
 	return (
-		<div className="text-center p-3 bg-background rounded-lg">
+		<div className="rounded-lg bg-destructive/10 border border-destructive/20 px-4 py-3 text-sm text-destructive">
 			{sanitizedError}
 		</div>
 	);
@@ -24,22 +24,24 @@ function Search() {
 
 export default function AuthErrorPage() {
 	return (
-		<div className="min-h-screen flex items-center justify-center bg-background p-4">
-			<Card className="w-full max-w-md bg-red-400 dark:bg-red-600">
-				<CardHeader className="text-center">
-					<CardTitle className="text-2xl font-bold">Error</CardTitle>
-				</CardHeader>
-				<CardContent className="space-y-4">
-					<Suspense>
-						<Search />
-					</Suspense>
-					<div className="flex flex-row">
-						<Button variant="secondary" asChild>
-							<Link href="/">Go back to Homepage</Link>
-						</Button>
-					</div>
-				</CardContent>
-			</Card>
+		<div className="flex items-center justify-center py-20">
+			<div className="glass-strong rounded-2xl p-8 w-full max-w-sm space-y-6">
+				<div className="text-center">
+					<AlertTriangle className="h-8 w-8 text-destructive mx-auto mb-3" />
+					<h1 className="text-lg font-semibold">Authentication Error</h1>
+					<p className="text-sm text-muted-foreground mt-1">
+						Something went wrong during sign in
+					</p>
+				</div>
+
+				<Suspense>
+					<ErrorMessage />
+				</Suspense>
+
+				<Button variant="outline" asChild className="w-full">
+					<Link href="/">Go back to Homepage</Link>
+				</Button>
+			</div>
 		</div>
 	);
 }

src/app/auth/signin/page.tsx

@@ -1,17 +1,12 @@
 "use client";
 
+import { motion } from "framer-motion";
+import { CalendarDays, Loader2 } from "lucide-react";
 import Link from "next/link";
 import { useRouter } from "next/navigation";
 import { useEffect, useState } from "react";
 import { toast } from "sonner";
 import { Button } from "@/components/ui/button";
-import {
-	Card,
-	CardContent,
-	CardDescription,
-	CardHeader,
-	CardTitle,
-} from "@/components/ui/card";
 import { signIn, useSession } from "@/lib/auth-client";
 
 export default function SignInPage() {
@@ -39,43 +34,46 @@ export default function SignInPage() {
 		}
 	};
 
-	if (isPending) {
-		return null;
-	}
-
-	if (session?.user) {
+	if (isPending || session?.user) {
 		return null;
 	}
 
 	return (
-		<div className="min-h-screen flex items-center justify-center bg-background p-4">
-			<Card className="w-full max-w-md">
-				<CardHeader className="text-center">
-					<CardTitle className="text-2xl font-bold">Welcome</CardTitle>
-					<CardDescription>
-						Sign in to access AI-powered calendar features
-					</CardDescription>
-				</CardHeader>
-				<CardContent className="space-y-4">
-					<Button
-						onClick={handleSignIn}
-						className="w-full"
-						size="lg"
-						disabled={isLoading}
-					>
-						{isLoading ? "Signing in..." : "Continue with Authentik"}
-					</Button>
+		<div className="min-h-screen flex items-center justify-center p-4">
+			<motion.div
+				initial={{ opacity: 0, y: 16 }}
+				animate={{ opacity: 1, y: 0 }}
+				transition={{ duration: 0.3 }}
+				className="glass-strong p-8 max-w-sm w-full text-center"
+			>
+				<div className="flex items-center justify-center gap-2 mb-6">
+					<CalendarDays className="h-6 w-6 text-primary" />
+					<h1 className="text-xl font-semibold tracking-tight">Local iCal</h1>
+				</div>
 
-					<div className="text-center">
-						<Link
-							href="/"
-							className="text-sm text-muted-foreground hover:underline"
-						>
-							Continue without signing in
-						</Link>
-					</div>
-				</CardContent>
-			</Card>
+				<p className="text-sm text-muted-foreground mb-6">
+					Sign in to unlock AI-powered event creation
+				</p>
+
+				<Button
+					onClick={handleSignIn}
+					className="w-full"
+					size="default"
+					disabled={isLoading}
+				>
+					{isLoading ? <Loader2 className="h-4 w-4 animate-spin mr-2" /> : null}
+					{isLoading ? "Signing in..." : "Continue with Authentik"}
+				</Button>
+
+				<div className="mt-4">
+					<Link
+						href="/"
+						className="text-xs text-muted-foreground hover:text-foreground transition-colors"
+					>
+						Continue without signing in
+					</Link>
+				</div>
+			</motion.div>
 		</div>
 	);
 }

src/app/auth/signout/page.tsx

@@ -1,16 +1,10 @@
 "use client";
 
+import { LogOut } from "lucide-react";
 import Link from "next/link";
 import { useRouter } from "next/navigation";
 import { useEffect } from "react";
 import { Button } from "@/components/ui/button";
-import {
-	Card,
-	CardContent,
-	CardDescription,
-	CardHeader,
-	CardTitle,
-} from "@/components/ui/card";
 import { signOut, useSession } from "@/lib/auth-client";
 
 export default function SignOutPage() {
@@ -33,37 +27,38 @@ export default function SignOutPage() {
 	}
 
 	return (
-		<div className="min-h-screen flex items-center justify-center bg-background p-4">
-			<Card className="w-full max-w-md">
-				<CardHeader className="text-center">
-					<CardTitle className="text-2xl font-bold">Sign Out</CardTitle>
-					<CardDescription>Are you sure you want to sign out?</CardDescription>
-				</CardHeader>
-				<CardContent className="space-y-4">
-					<div className="text-center p-3 bg-muted rounded-lg">
-						<div className="text-sm text-muted-foreground">
-							Currently signed in as
-						</div>
-						<div className="font-medium">
-							{session.user?.name || session.user?.email}
-						</div>
-					</div>
+		<div className="flex items-center justify-center py-20">
+			<div className="glass-strong rounded-2xl p-8 w-full max-w-sm space-y-6">
+				<div className="text-center">
+					<LogOut className="h-8 w-8 text-muted-foreground mx-auto mb-3" />
+					<h1 className="text-lg font-semibold">Sign Out</h1>
+					<p className="text-sm text-muted-foreground mt-1">
+						Are you sure you want to sign out?
+					</p>
+				</div>
 
-					<div className="grid grid-cols-2 gap-3">
-						<Button
-							onClick={handleSignOut}
-							variant="destructive"
-							className="w-full"
-						>
-							Sign Out
-						</Button>
-
-						<Button variant="outline" asChild>
-							<Link href="/">Cancel</Link>
-						</Button>
+				<div className="rounded-lg bg-muted/40 px-4 py-3 text-center">
+					<div className="text-xs text-muted-foreground mb-0.5">
+						Signed in as
 					</div>
-				</CardContent>
-			</Card>
+					<div className="text-sm font-medium">
+						{session.user?.name || session.user?.email}
+					</div>
+				</div>
+
+				<div className="grid grid-cols-2 gap-3">
+					<Button
+						onClick={handleSignOut}
+						variant="destructive"
+						className="w-full"
+					>
+						Sign Out
+					</Button>
+					<Button variant="outline" asChild>
+						<Link href="/">Cancel</Link>
+					</Button>
+				</div>
+			</div>
 		</div>
 	);
 }