Split up files and add templating

Signed-off-by: Marcel Müller <neikos@neikos.email>

nixie-server/templates/protected.tera.html

@@ -0,0 +1,9 @@
+{% extends "base.tera.html" %}
+
+{% block title %}
+Protected Page
+{% endblock title %}
+
+{% block content %}
+    This is super secret content!
+{% endblock content %}