v0.12.0 - Add modular system architecture with user-based module access

- Add Modules and UserModules database tables
- Create home page with module selection grid
- Implement per-user module assignment in user management
- Add route guards for module access control
- Refactor navigation: login -> home -> modules, admin console via button
- Add Font Awesome icons

templates/staff_dashboard.html

@@ -7,16 +7,19 @@
     <!-- Mode Selector (only for admins) -->
     {% if session.role in ['owner', 'admin'] %}
     <div class="mode-selector">
-        <a href="{{ url_for('dashboard') }}" class="mode-btn">
-            Admin Console
+        <a href="{{ url_for('admin_dashboard') }}" class="mode-btn">
+            👔 Admin Console
         </a>
         <button class="mode-btn mode-btn-active">
-            Scanning Mode
+            📦 Scanning Mode
         </button>
     </div>
     {% endif %}
 
     <div class="dashboard-header">
+        <a href="{{ url_for('home') }}" class="btn btn-secondary btn-sm" style="margin-bottom: var(--space-md);">
+            <i class="fa-solid fa-arrow-left"></i> Back to Home
+        </a>
         <h1 class="page-title">Select Count Session</h1>
     </div>