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/database/document-sequences-table.ts

@@ -0,0 +1,17 @@
+import { integer, pgTable, primaryKey, varchar } from 'drizzle-orm/pg-core';
+
+/**
+ * Per-prefix daily counters used to generate document codes.
+ */
+export const documentSequences = pgTable(
+  'document_sequences',
+  {
+    prefix: varchar('prefix', { length: 8 }).notNull(),
+    period: varchar('period', { length: 8 }).notNull(),
+    lastValue: integer('last_value').notNull(),
+  },
+  (t) => [primaryKey({ columns: [t.prefix, t.period] })],
+);
+
+export type DocumentSequenceRow = typeof documentSequences.$inferSelect;
+export type NewDocumentSequenceRow = typeof documentSequences.$inferInsert;