Use new categories correctly in existing components and handle category names with commas

inventory-server/src/routes/purchase-orders.js

@@ -243,7 +243,7 @@ router.get('/cost-analysis', async (req, res) => {
     
     const [analysis] = await pool.query(`
       SELECT 
-        p.categories,
+        c.name as categories,
         COUNT(DISTINCT po.product_id) as unique_products,
         ROUND(AVG(po.cost_price), 2) as avg_cost,
         MIN(po.cost_price) as min_cost,
@@ -254,7 +254,9 @@ router.get('/cost-analysis', async (req, res) => {
         SUM(po.ordered * po.cost_price) as total_spend
       FROM purchase_orders po
       JOIN products p ON po.product_id = p.product_id
-      GROUP BY p.categories
+      JOIN product_categories pc ON p.product_id = pc.product_id
+      JOIN categories c ON pc.category_id = c.id
+      GROUP BY c.name
       ORDER BY total_spend DESC
     `);