feat(04-01): redesign LoginPage with brand presence and OAuth icons

- Change background from bg-background to bg-muted/60
- Add border-t-4 border-t-primary shadow-lg card accent
- Add favicon.svg logo above CardTitle
- Add auth.loginSubtitle below title
- Add Google SVG icon and GitHub SVG icon to OAuth buttons
- Add gap-2 to OAuth button className for icon/text spacing
- Add auth.loginSubtitle and auth.registerSubtitle to en.json and de.json

src/i18n/de.json

@@ -19,7 +19,9 @@
     "displayName": "Anzeigename",
     "noAccount": "Noch kein Konto?",
     "hasAccount": "Bereits ein Konto?",
-    "orContinueWith": "Oder weiter mit"
+    "orContinueWith": "Oder weiter mit",
+    "loginSubtitle": "Melde dich bei deinem Konto an",
+    "registerSubtitle": "Erstelle ein neues Konto"
   },
   "categories": {
     "title": "Kategorien",

src/i18n/en.json

@@ -19,7 +19,9 @@
     "displayName": "Display Name",
     "noAccount": "Don't have an account?",
     "hasAccount": "Already have an account?",
-    "orContinueWith": "Or continue with"
+    "orContinueWith": "Or continue with",
+    "loginSubtitle": "Sign in to your account",
+    "registerSubtitle": "Create a new account"
   },
   "categories": {
     "title": "Categories",

src/pages/LoginPage.tsx

@@ -0,0 +1,118 @@
+import { useState } from "react"
+import { Link, useNavigate } from "react-router-dom"
+import { useTranslation } from "react-i18next"
+import { useAuth } from "@/hooks/useAuth"
+import { Button } from "@/components/ui/button"
+import { Input } from "@/components/ui/input"
+import { Label } from "@/components/ui/label"
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
+import { Separator } from "@/components/ui/separator"
+
+export default function LoginPage() {
+  const { t } = useTranslation()
+  const { signIn, signInWithOAuth } = useAuth()
+  const navigate = useNavigate()
+  const [email, setEmail] = useState("")
+  const [password, setPassword] = useState("")
+  const [error, setError] = useState("")
+  const [loading, setLoading] = useState(false)
+
+  async function handleSubmit(e: React.FormEvent) {
+    e.preventDefault()
+    setError("")
+    setLoading(true)
+    try {
+      await signIn(email, password)
+      navigate("/")
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"))
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <div className="flex min-h-screen items-center justify-center bg-muted/60 p-4">
+      <Card className="w-full max-w-sm border-t-4 border-t-primary shadow-lg">
+        <CardHeader className="text-center pb-4">
+          <img src="/favicon.svg" alt="" className="mx-auto mb-3 size-10" aria-hidden="true" />
+          <CardTitle className="text-2xl">{t("app.title")}</CardTitle>
+          <p className="text-sm text-muted-foreground">{t("auth.loginSubtitle")}</p>
+        </CardHeader>
+        <CardContent>
+          <form onSubmit={handleSubmit} className="space-y-4">
+            <div className="space-y-2">
+              <Label htmlFor="email">{t("auth.email")}</Label>
+              <Input
+                id="email"
+                type="email"
+                value={email}
+                onChange={(e) => setEmail(e.target.value)}
+                required
+                autoComplete="email"
+              />
+            </div>
+            <div className="space-y-2">
+              <Label htmlFor="password">{t("auth.password")}</Label>
+              <Input
+                id="password"
+                type="password"
+                value={password}
+                onChange={(e) => setPassword(e.target.value)}
+                required
+                autoComplete="current-password"
+              />
+            </div>
+            {error && (
+              <p className="text-sm text-destructive">{error}</p>
+            )}
+            <Button type="submit" className="w-full" disabled={loading}>
+              {t("auth.login")}
+            </Button>
+          </form>
+
+          <div className="mt-4">
+            <div className="relative">
+              <Separator />
+              <span className="absolute left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2 bg-card px-2 text-xs text-muted-foreground">
+                {t("auth.orContinueWith")}
+              </span>
+            </div>
+            <div className="mt-4 flex gap-2">
+              <Button
+                variant="outline"
+                className="flex-1 gap-2"
+                onClick={() => signInWithOAuth("google")}
+              >
+                <svg className="size-4" viewBox="0 0 24 24" aria-hidden="true">
+                  <path d="M22.56 12.25c0-.78-.07-1.53-.2-2.25H12v4.26h5.92a5.06 5.06 0 0 1-2.2 3.32v2.77h3.57c2.08-1.92 3.27-4.74 3.27-8.1z" fill="#4285F4"/>
+                  <path d="M12 23c2.97 0 5.46-.98 7.28-2.66l-3.57-2.77c-.98.66-2.23 1.06-3.71 1.06-2.86 0-5.29-1.93-6.16-4.53H2.18v2.84C3.99 20.53 7.7 23 12 23z" fill="#34A853"/>
+                  <path d="M5.84 14.09c-.22-.66-.35-1.36-.35-2.09s.13-1.43.35-2.09V7.07H2.18C1.43 8.55 1 10.22 1 12s.43 3.45 1.18 4.93l2.85-2.22.81-.62z" fill="#FBBC05"/>
+                  <path d="M12 5.38c1.62 0 3.06.56 4.21 1.64l3.15-3.15C17.45 2.09 14.97 1 12 1 7.7 1 3.99 3.47 2.18 7.07l3.66 2.84c.87-2.6 3.3-4.53 6.16-4.53z" fill="#EA4335"/>
+                </svg>
+                Google
+              </Button>
+              <Button
+                variant="outline"
+                className="flex-1 gap-2"
+                onClick={() => signInWithOAuth("github")}
+              >
+                <svg className="size-4" viewBox="0 0 24 24" fill="currentColor" aria-hidden="true">
+                  <path d="M12 2C6.477 2 2 6.484 2 12.017c0 4.425 2.865 8.18 6.839 9.504.5.092.682-.217.682-.483 0-.237-.008-.868-.013-1.703-2.782.605-3.369-1.343-3.369-1.343-.454-1.158-1.11-1.466-1.11-1.466-.908-.62.069-.608.069-.608 1.003.07 1.531 1.032 1.531 1.032.892 1.53 2.341 1.088 2.91.832.092-.647.35-1.088.636-1.338-2.22-.253-4.555-1.113-4.555-4.951 0-1.093.39-1.988 1.029-2.688-.103-.253-.446-1.272.098-2.65 0 0 .84-.27 2.75 1.026A9.564 9.564 0 0 1 12 6.844a9.59 9.59 0 0 1 2.504.337c1.909-1.296 2.747-1.027 2.747-1.027.546 1.379.202 2.398.1 2.651.64.7 1.028 1.595 1.028 2.688 0 3.848-2.339 4.695-4.566 4.943.359.309.678.92.678 1.855 0 1.338-.012 2.419-.012 2.747 0 .268.18.58.688.482A10.02 10.02 0 0 0 22 12.017C22 6.484 17.522 2 12 2z"/>
+                </svg>
+                GitHub
+              </Button>
+            </div>
+          </div>
+
+          <p className="mt-4 text-center text-sm text-muted-foreground">
+            {t("auth.noAccount")}{" "}
+            <Link to="/register" className="text-primary underline">
+              {t("auth.register")}
+            </Link>
+          </p>
+        </CardContent>
+      </Card>
+    </div>
+  )
+}