Add new filter options and metrics to product filters and pages; enhance SQL schema for financial calculations

inventory-server/db/schema.sql

@@ -7,7 +7,7 @@ BEGIN
     -- Check which table is being updated and use the appropriate column
     IF TG_TABLE_NAME = 'categories' THEN
         NEW.updated_at = CURRENT_TIMESTAMP;
-    ELSE
+    ELSIF TG_TABLE_NAME IN ('products', 'orders', 'purchase_orders') THEN
         NEW.updated = CURRENT_TIMESTAMP;
     END IF;
     RETURN NEW;
@@ -91,6 +91,7 @@ CREATE TABLE categories (
     description TEXT,
     created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+    updated TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
     status VARCHAR(20) DEFAULT 'active',
     FOREIGN KEY (parent_id) REFERENCES categories(cat_id)
 );