feat: add boilerplate

app/templates/admin_login.html

@@ -0,0 +1,14 @@
+{% extends "base.html" %}
+{% block title %}Admin · Guess the RAL{% endblock %}
+{% block content %}
+<section class="hero pixel-panel">
+  <h1>ADMIN</h1>
+  {% if error %}<p class="alert">{{ error }}</p>{% endif %}
+  <form class="stack" method="post" action="/admin/login">
+    <label>PASSWORD
+      <input type="password" name="password" required />
+    </label>
+    <button class="btn" type="submit">ENTER</button>
+  </form>
+</section>
+{% endblock %}