Fix navigation and logo issues (Issues #13, #14)

- Add navigation bar to admin setup page (Fixes issue #14)
- Make logo clickable to go to front page in admin setup (Fixes issue #13)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

templates/admin_setup.html

@@ -3,10 +3,13 @@
 {% block title %}Create Admin Account - BalanceBoard{% endblock %}
 
 {% block content %}
+{% include '_nav.html' %}
 <div class="auth-container">
     <div class="auth-card">
         <div class="auth-logo">
-            <img src="{{ url_for('serve_logo') }}" alt="BalanceBoard Logo">
+            <a href="{{ url_for('index') }}">
+                <img src="{{ url_for('serve_logo') }}" alt="BalanceBoard Logo" style="max-width: 80px; border-radius: 50%;">
+            </a>
             <h1><span class="balance">balance</span><span class="board">Board</span></h1>
             <p style="color: var(--text-secondary); margin-top: 8px;">Create Administrator Account</p>
         </div>