feat: add auth router with login/logout/me and login template

app/templates/auth/login.html

@@ -0,0 +1,54 @@
+{% extends "base.html" %}
+
+{% block title %}Anmelden · EFI Hub{% endblock %}
+
+{% block content %}
+<div class="min-h-[80vh] flex items-center justify-center px-4">
+  <div class="w-full max-w-sm">
+
+    <div class="text-center mb-8">
+      <p class="text-xs font-semibold uppercase tracking-widest text-efi mb-1">
+        Fakultät EFI · TH Nürnberg
+      </p>
+      <h1 class="text-xl font-bold text-gray-900">Anmelden</h1>
+      <p class="text-sm text-gray-500 mt-1">Bitte melde dich mit deinen Zugangsdaten an.</p>
+    </div>
+
+    {% if error %}
+    <div class="mb-4 px-4 py-3 rounded-md bg-red-50 border border-red-200 text-sm text-red-700">
+      {{ error }}
+    </div>
+    {% endif %}
+
+    <form method="post" action="/auth/login" class="bg-white rounded-lg border border-gray-200 shadow-sm p-6 space-y-4">
+      <div>
+        <label class="block text-xs font-semibold text-gray-600 uppercase tracking-wide mb-1" for="username">
+          Benutzername
+        </label>
+        <input
+          id="username" name="username" type="text"
+          class="w-full border border-gray-300 rounded-md px-3 py-2 text-sm focus:outline-none focus:border-efi focus:ring-1 focus:ring-efi"
+          autocomplete="username" autofocus required
+        >
+      </div>
+      <div>
+        <label class="block text-xs font-semibold text-gray-600 uppercase tracking-wide mb-1" for="password">
+          Passwort
+        </label>
+        <input
+          id="password" name="password" type="password"
+          class="w-full border border-gray-300 rounded-md px-3 py-2 text-sm focus:outline-none focus:border-efi focus:ring-1 focus:ring-efi"
+          autocomplete="current-password" required
+        >
+      </div>
+      <button
+        type="submit"
+        class="w-full bg-efi text-white text-sm font-semibold py-2 px-4 rounded-md hover:opacity-90 transition-opacity"
+      >
+        Anmelden
+      </button>
+    </form>
+
+  </div>
+</div>
+{% endblock %}