feat: initialize full-stack architecture with backend routes, database schema, and glassmorphic frontend UI

backend/routes/finance.py

@@ -0,0 +1,47 @@
+from flask import Blueprint, request, jsonify
+from ..middleware import token_required
+
+finance_blueprint = Blueprint('finance', __name__)
+
+@finance_blueprint.route('/finance/calculate-pnl', methods=['POST'])
+@token_required
+def calculate_pnl(current_user_id):
+    """
+    Расчет чистой прибыли и маржинальности.
+    """
+    data = request.json
+    
+    # Входные данные
+    sale_price = float(data.get('sale_price', 0))       # Цена продажи
+    purchase_price = float(data.get('purchase_price', 0)) # Себестоимость (закупка)
+    logistics = float(data.get('logistics', 0))         # Логистика
+    commission_pct = float(data.get('commission_pct', 0)) # Комиссия маркетплейса %
+    tax_pct = float(data.get('tax_pct', 6))             # Налог % (УСН)
+    adv_per_unit = float(data.get('adv_per_unit', 0))   # Реклама на 1 шт
+    other_costs = float(data.get('other_costs', 0))     # Прочие расходы (упаковка и т.д.)
+
+    # Расчеты
+    marketplace_commission = sale_price * (commission_pct / 100)
+    taxes = sale_price * (tax_pct / 100)
+    
+    total_costs = (
+        purchase_price + 
+        logistics + 
+        marketplace_commission + 
+        taxes + 
+        adv_per_unit + 
+        other_costs
+    )
+    
+    net_profit = sale_price - total_costs
+    margin = (net_profit / sale_price * 100) if sale_price > 0 else 0
+    roi = (net_profit / purchase_price * 100) if purchase_price > 0 else 0
+
+    return jsonify({
+        "net_profit": round(net_profit, 2),
+        "margin": round(margin, 2),
+        "roi": round(roi, 2),
+        "total_costs": round(total_costs, 2),
+        "tax_amount": round(taxes, 2),
+        "commission_amount": round(marketplace_commission, 2)
+    })