Refactor application to MVC architecture with Flask blueprints

Major architectural refactoring to improve code organization, maintainability, and scalability:

- Implement MVC pattern with clear separation of concerns
- Organize code into blueprints for different functional areas (main, tenant, admin, api)
- Create models layer to encapsulate all database operations
- Create services layer for business logic (auth, product, barcode)
- Implement application factory pattern for better testability
- Add environment-based configuration management
- Remove old monolithic app.py and consolidate routes

New structure:
- app/models/ - Database operations (Tenant, Product, ARField, Settings)
- app/services/ - Business logic (Auth, Product, Barcode services)
- app/blueprints/ - Controllers organized by function
- app/config.py - Environment configurations
- run.py - Application entry point

All routes remain backward compatible. No changes to API or templates functionality.

src/app/templates/admin/all_barcodes.html

@@ -0,0 +1,149 @@
+{% extends "layout.html" %}
+
+{% block title %}All Barcodes - {{ tenant.name }} - KCAP Demo Server{% endblock %}
+
+{% block extra_css %}
+<style>
+    /* Screen styles */
+    @media screen {
+        .barcode-grid {
+            display: grid;
+            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
+            gap: 20px;
+            padding: 20px 0;
+        }
+
+        .barcode-item {
+            border: 1px solid #ddd;
+            padding: 15px;
+            border-radius: 8px;
+            text-align: center;
+            background: white;
+            box-shadow: 0 2px 4px rgba(0,0,0,0.1);
+        }
+
+        .barcode-item img {
+            max-width: 100%;
+            height: auto;
+            margin: 10px 0;
+        }
+
+        .barcode-item .product-id {
+            font-weight: bold;
+            font-size: 1.1em;
+            margin-bottom: 10px;
+            color: #333;
+        }
+
+        .print-buttons {
+            margin-bottom: 20px;
+        }
+    }
+
+    /* Print styles */
+    @media print {
+        /* Hide everything except barcodes */
+        nav, .navbar, .print-buttons, .alert, .btn {
+            display: none !important;
+        }
+
+        body {
+            margin: 0;
+            padding: 0;
+        }
+
+        .container {
+            max-width: 100% !important;
+            padding: 0 !important;
+            margin: 0 !important;
+        }
+
+        /* Grid layout for print */
+        .barcode-grid {
+            display: grid;
+            grid-template-columns: repeat(3, 1fr);
+            gap: 10px;
+            padding: 10px;
+            page-break-inside: avoid;
+        }
+
+        .barcode-item {
+            border: 1px solid #ddd;
+            padding: 10px;
+            text-align: center;
+            page-break-inside: avoid;
+            background: white;
+        }
+
+        .barcode-item img {
+            max-width: 100%;
+            height: auto;
+            display: block;
+            margin: 5px auto;
+        }
+
+        .barcode-item .product-id {
+            font-weight: bold;
+            font-size: 0.9em;
+            margin-bottom: 5px;
+            color: #000;
+        }
+
+        /* Page breaks */
+        @page {
+            margin: 0.5cm;
+        }
+    }
+</style>
+{% endblock %}
+
+{% block content %}
+<div class="row mt-4">
+    <div class="col-md-12">
+        <div class="alert alert-info">
+            <strong>Current Tenant:</strong> {{ tenant.name }} (ID: {{ tenant.id }})
+            <div class="mt-2">
+                <a href="{{ url_for('tenant_index', tenant_id=tenant.id) }}" class="btn btn-sm btn-secondary">Back to Dashboard</a>
+            </div>
+        </div>
+
+        <div class="print-buttons d-flex justify-content-between align-items-center mb-4">
+            <h1>All Product Barcodes</h1>
+            <button onclick="window.print()" class="btn btn-primary">
+                <i class="bi bi-printer"></i> Print Barcodes
+            </button>
+        </div>
+
+        {% if products %}
+        <div class="barcode-grid">
+            {% for product_id, product_data in products.items() %}
+            <div class="barcode-item">
+                <div class="product-id">{{ product_id }}</div>
+                <img src="/{{ tenant.id }}/barcodes/{{ product_id }}_{{ barcode_type }}.png"
+                     alt="Barcode for {{ product_id }}"
+                     onerror="this.src='data:image/svg+xml,%3Csvg xmlns=\'http://www.w3.org/2000/svg\' width=\'200\' height=\'100\'%3E%3Crect width=\'200\' height=\'100\' fill=\'%23f0f0f0\'/%3E%3Ctext x=\'50%25\' y=\'50%25\' dominant-baseline=\'middle\' text-anchor=\'middle\' font-family=\'Arial\' font-size=\'12\' fill=\'%23999\'%3EBarcode unavailable%3C/text%3E%3C/svg%3E';">
+            </div>
+            {% endfor %}
+        </div>
+        {% else %}
+        <div class="alert alert-info">
+            No products available to generate barcodes.
+        </div>
+        {% endif %}
+    </div>
+</div>
+{% endblock %}
+
+{% block extra_js %}
+<script>
+    // Optional: Automatically print when page loads if requested via URL parameter
+    const urlParams = new URLSearchParams(window.location.search);
+    if (urlParams.get('autoprint') === 'true') {
+        window.onload = function() {
+            setTimeout(function() {
+                window.print();
+            }, 500);
+        };
+    }
+</script>
+{% endblock %}