Add employees management module with database schema and validation

- Introduced `EmployeesModule` to manage employee data, including read and write controllers.
- Created database migrations for the `employees` table, including constraints and unique indexes.
- Implemented validation for employee fields such as name, code, and position with corresponding utility functions.
- Developed service and repository layers for handling employee data operations.
- Added unit tests for the employees service, repository, and controllers to ensure functionality and correctness.
- Updated application module to include the new `EmployeesModule` for better organization.

src/database/employees-table.ts

@@ -0,0 +1,23 @@
+import { pgTable, text, uniqueIndex, uuid, varchar } from 'drizzle-orm/pg-core';
+import { primaryEntityColumns } from './primary-entity-columns';
+import { users } from './schema';
+
+/**
+ * Employees (primary aggregate).
+ * Kept in a separate module so Drizzle's table type stays resolvable.
+ */
+export const employees = pgTable(
+  'employees',
+  {
+    id: uuid('id').defaultRandom().notNull().primaryKey(),
+    code: varchar('code', { length: 16 }).notNull(),
+    name: varchar('name', { length: 64 }).notNull(),
+    phone: text('phone').notNull(),
+    position: text('position').notNull(),
+    ...primaryEntityColumns(users),
+  },
+  (t) => [uniqueIndex('employees_code_unique').on(t.code)],
+);
+
+export type EmployeeRow = typeof employees.$inferSelect;
+export type NewEmployeeRow = typeof employees.$inferInsert;