add frontend application structure with authentication, generation features, and integration tests

frontend/app/templates/login.html

@@ -0,0 +1,17 @@
+{% extends "base.html" %}
+{% block title %}Log in — AI Allucanget{% endblock %}
+{% block content %}
+<div class="card">
+  <h1>Log in</h1>
+  <form method="post">
+    <label for="email">Email</label>
+    <input id="email" name="email" type="email" required autofocus>
+
+    <label for="password">Password</label>
+    <input id="password" name="password" type="password" required>
+
+    <button type="submit">Log in</button>
+  </form>
+  <p>No account? <a href="{{ url_for('register') }}">Register</a></p>
+</div>
+{% endblock %}