Add products and sales management modules with database schema and validation

- Introduced `ProductsModule` to manage product data, including read and write controllers.
- Created database migrations for the `products`, `sales_requests`, `sales_orders`, `sales_invoices`, and related tables, including constraints and unique indexes.
- Implemented validation for product fields such as code, name, unit, and brand with corresponding utility functions.
- Developed service and repository layers for handling product and sales data operations.
- Added unit tests for the products and sales services, repositories, and controllers to ensure functionality and correctness.
- Updated application module to include the new `ProductsModule` and related sales modules for better organization.

src/modules/sales/shared/sales-fields.spec.ts

@@ -0,0 +1,25 @@
+import {
+  isValidDocumentCode,
+  isValidImageUrl,
+  isValidLatitude,
+} from './sales-fields';
+
+describe('sales fields', () => {
+  it('accepts generated and user document codes', () => {
+    expect(isValidDocumentCode('SR-20260824-0001')).toBe(true);
+    expect(isValidDocumentCode('REQ_01')).toBe(true);
+    expect(isValidDocumentCode('')).toBe(false);
+    expect(isValidDocumentCode('SR 1')).toBe(false);
+  });
+
+  it('accepts http(s) image URLs only', () => {
+    expect(isValidImageUrl('https://cdn.example.com/a.png')).toBe(true);
+    expect(isValidImageUrl('ftp://x/a.png')).toBe(false);
+    expect(isValidImageUrl('not-a-url')).toBe(false);
+  });
+
+  it('validates latitude', () => {
+    expect(isValidLatitude(-6.2)).toBe(true);
+    expect(isValidLatitude(100)).toBe(false);
+  });
+});