Implement print labels module with PDF generation, QZ Tray integration, and theme support

- Migrate print_labels.html and print_lost_labels.html to standalone pages with header and theme toggle
- Implement dark/light theme support using data-theme attribute and CSS variables
- Add PDF generation endpoints for single and batch label printing
- Copy pdf_generator.py from original app with full label formatting (80mm x 105mm)
- Fix data response handling to correctly access data.orders from API endpoints
- Synchronize table text sizes across both print pages
- Remove help buttons from print pages
- Database column rename: data_livrara → data_livrare for consistency
- Update routes to use correct database column names
- Add 7 test orders to database (4 unprinted, 3 printed)
- Implement QZ Tray integration with PDF fallback for label printing
- All CSS uses theme variables for dark/light mode synchronization

app/modules/labels/routes.py

@@ -5,6 +5,7 @@ Handles label printing pages and API endpoints
 from flask import Blueprint, render_template, session, redirect, url_for, jsonify, request
 import logging
 
+from app.database import get_db
 from .print_module import (
     get_unprinted_orders_data, 
     get_printed_orders_data,
@@ -35,6 +36,15 @@ def print_module():
     return render_template('modules/labels/print_module.html')
 
 
+@labels_bp.route('/print-labels', methods=['GET'])
+def print_labels():
+    """Original print labels interface - complete copy from quality app"""
+    if 'user_id' not in session:
+        return redirect(url_for('main.login'))
+    
+    return render_template('modules/labels/print_labels.html')
+
+
 @labels_bp.route('/print-lost-labels', methods=['GET'])
 def print_lost_labels():
     """Print lost/missing labels interface"""
@@ -74,6 +84,28 @@ def help(page='index'):
             </ol>
             '''
         },
+        'print_labels': {
+            'title': 'Print Labels Help',
+            'content': '''
+            <h3>Print Labels - Thermal Printer Guide</h3>
+            <p>This module helps you print labels directly to thermal printers.</p>
+            <h4>Features:</h4>
+            <ul>
+                <li>Live label preview in thermal format</li>
+                <li>Real-time printer selection</li>
+                <li>Barcode generation</li>
+                <li>PDF export fallback</li>
+                <li>Batch printing support</li>
+            </ul>
+            <h4>How to use:</h4>
+            <ol>
+                <li>Select orders from the list</li>
+                <li>Preview labels in the preview pane</li>
+                <li>Select your printer</li>
+                <li>Click "Print Labels" to send to printer</li>
+            </ol>
+            '''
+        },
         'print_lost_labels': {
             'title': 'Print Lost Labels Help',
             'content': '''
@@ -198,3 +230,110 @@ def api_update_printed_status(order_id):
     except Exception as e:
         logger.error(f"Error updating order status: {e}")
         return jsonify({'success': False, 'error': str(e)}), 500
+
+
+@labels_bp.route('/api/generate-pdf', methods=['POST'], endpoint='api_generate_pdf')
+def api_generate_pdf():
+    """Generate single label PDF for thermal printing via QZ Tray"""
+    if 'user_id' not in session:
+        return jsonify({'error': 'Unauthorized'}), 401
+    
+    try:
+        from .pdf_generator import LabelPDFGenerator
+        
+        # Get order data from request
+        order_data = request.get_json()
+        
+        if not order_data:
+            return jsonify({'error': 'No order data provided'}), 400
+        
+        # Extract piece number and total pieces for sequential numbering
+        piece_number = order_data.get('piece_number', 1)
+        total_pieces = order_data.get('total_pieces', 1)
+        
+        logger.info(f"Generating single label PDF for piece {piece_number} of {total_pieces}")
+        
+        # Initialize PDF generator in thermal printer optimized mode
+        pdf_generator = LabelPDFGenerator(paper_saving_mode=True)
+        
+        # Generate single label PDF with specific piece number for sequential CP numbering
+        pdf_buffer = pdf_generator.generate_single_label_pdf(order_data, piece_number, total_pieces, printer_optimized=True)
+        
+        # Create response with PDF data
+        from flask import make_response
+        response = make_response(pdf_buffer.getvalue())
+        response.headers['Content-Type'] = 'application/pdf'
+        response.headers['Content-Disposition'] = f'inline; filename="label_{piece_number:03d}.pdf"'
+        
+        return response
+        
+    except Exception as e:
+        logger.error(f"Error generating PDF: {e}")
+        return jsonify({'error': str(e)}), 500
+
+
+@labels_bp.route('/api/generate-pdf/<int:order_id>/true', methods=['POST'], endpoint='api_generate_batch_pdf')
+def api_generate_batch_pdf(order_id):
+    """Generate all label PDFs for an order and mark as printed"""
+    if 'user_id' not in session:
+        return jsonify({'error': 'Unauthorized'}), 401
+    
+    try:
+        from .pdf_generator import LabelPDFGenerator
+        
+        # Get order data from database
+        conn = get_db()
+        cursor = conn.cursor()
+        
+        cursor.execute("""
+            SELECT id, comanda_productie, cod_articol, descr_com_prod, cantitate,
+                   com_achiz_client, nr_linie_com_client, customer_name,
+                   customer_article_number, open_for_order, line_number,
+                   created_at, updated_at, printed_labels, data_livrare, dimensiune
+            FROM order_for_labels 
+            WHERE id = %s
+        """, (order_id,))
+        
+        row = cursor.fetchone()
+        
+        if not row:
+            cursor.close()
+            return jsonify({'error': 'Order not found'}), 404
+        
+        # Create order data dictionary
+        columns = [col[0] for col in cursor.description]
+        order_data = {columns[i]: row[i] for i in range(len(columns))}
+        
+        # Ensure date fields are strings
+        if order_data.get('data_livrare'):
+            order_data['data_livrare'] = str(order_data['data_livrare'])
+        
+        cursor.close()
+        
+        logger.info(f"Generating batch PDF for order {order_id} with {order_data.get('cantitate', 0)} labels")
+        
+        # Initialize PDF generator
+        pdf_generator = LabelPDFGenerator(paper_saving_mode=True)
+        
+        # Get quantity from order data
+        quantity = int(order_data.get('cantitate', 1))
+        
+        # Generate PDF with all labels
+        pdf_buffer = pdf_generator.generate_labels_pdf(order_data, quantity, printer_optimized=True)
+        
+        # Mark order as printed
+        success = update_order_printed_status(order_id, True)
+        if not success:
+            logger.warning(f"Failed to mark order {order_id} as printed, but PDF was generated")
+        
+        # Create response with PDF data
+        from flask import make_response
+        response = make_response(pdf_buffer.getvalue())
+        response.headers['Content-Type'] = 'application/pdf'
+        response.headers['Content-Disposition'] = f'attachment; filename="labels_{order_data.get("comanda_productie", "unknown")}.pdf"'
+        
+        return response
+        
+    except Exception as e:
+        logger.error(f"Error generating batch PDF: {e}")
+        return jsonify({'error': str(e)}), 500