Implement basic login function; add basic styling

templates/dashboard.html.twig

@@ -0,0 +1,11 @@
+{% extends "base.html.twig" %}
+
+{% block title %}Dashboard{% endblock %}
+
+{% block content %}
+    <h2>Dashboard</h2>
+
+    <p>Hello, {{ username }}!</p>
+
+    <a href="/logout">Logout.</a>
+{% endblock %}