feat: production-ready domain control dashboard

internal/web/templates/login.html

@@ -0,0 +1,18 @@
+{{define "login"}}{{template "layout" .}}{{end}}
+{{define "content"}}
+<section class="auth-card">
+  <div class="auth-brand"><span>DD</span> DynDNS Console</div>
+  <h1>Anmelden</h1>
+  <form action="/login" method="post" class="stacked-form">
+    <input type="hidden" name="csrf" value="{{.CSRF}}">
+    <label>Benutzername
+      <input name="username" type="text" autocomplete="username" required autofocus>
+    </label>
+    <label>Passwort
+      <input name="password" type="password" autocomplete="current-password" required>
+    </label>
+    <button class="button button-primary" type="submit">Anmelden <span aria-hidden="true">→</span></button>
+  </form>
+  <div class="login-meta">Sitzungen laufen nach acht Stunden automatisch ab.</div>
+</section>
+{{end}}