Add image upload preview functionality; update titles and templates for consistency

Co-authored-by: Copilot <copilot@github.com>

frontend/app/templates/dashboard.html

@@ -1,6 +1,5 @@
-{% extends "base.html" %}
-{% block title %}Dashboard — AI Allucanget{% endblock %}
-{% block content %}
+{% extends "base.html" %} {% block title %}Dashboard — All You Can GET AI{%
+endblock %} {% block content %}
 <div class="card">
   <h1>Welcome{% if user.get('email') %}, {{ user.email }}{% endif %}</h1>
   <p>Role: <strong>{{ user.get('role', 'user') }}</strong></p>