test: complete Wave 2 - all entity factories + documentation

- tests/fixtures/factory.ts: Config/Database + 6 additional factories (547 lines total)
  - UserFactory (3 methods: createAdmin, createUserDefault, createGuest)
  - OrderFactory (2 methods: createOrder, createOrders)
  - MaterialFactory (2 methods: createMaterial, createMaterials)
  - ConfigFactory (1 method: createErpConfig)
  - DatabaseFactory (1 method: createDatabaseConfig)
  - ExtractResultFactory (2 methods)
  - CleanerResultFactory (2 methods)
  - AuditLogFactory (1 method)
  - UpdateReleaseFactory (1 method)
  - ProductionInputFactory (1 method)
  - ValidationErrorFactory (1 method)
  Total: 17 factory methods across 10 factory classes

- Test coverage:
  - user-factory.test.ts: 3 tests
  - order-material-factory.test.ts: 4 tests
  - config-factory.test.ts: 5 tests
  - other-factories.test.ts: 15 tests
  Total: 27 factory tests

- docs/TEST_FACTORY_USAGE.md: User guide with examples (152 lines)

All factories support overrides customization and follow the <=100 lines per factory constraint.

tests/fixtures/config-factory.test.ts

@@ -0,0 +1,69 @@
+/**
+ * ConfigFactory and DatabaseFactory Unit Tests
+ */
+
+import { describe, it, expect } from 'vitest'
+import { ConfigFactory, DatabaseFactory } from './factory'
+
+describe('ConfigFactory', () => {
+  it('creates ERP config with default values', () => {
+    const config = ConfigFactory.createErpConfig()
+
+    expect(config.url).toBe('https://test-erp.example.com')
+    expect(config.username).toBe('test_user')
+    expect(config.password).toBe('test_password')
+  })
+
+  it('applies overrides to ERP config', () => {
+    const config = ConfigFactory.createErpConfig({
+      url: 'https://custom-erp.example.com',
+      username: 'admin',
+      password: 'secret123'
+    })
+
+    expect(config.url).toBe('https://custom-erp.example.com')
+    expect(config.username).toBe('admin')
+    expect(config.password).toBe('secret123')
+  })
+})
+
+describe('DatabaseFactory', () => {
+  it('creates MySQL config with default values', () => {
+    const config = DatabaseFactory.createDatabaseConfig('mysql')
+
+    expect(config.type).toBe('mysql')
+    expect(config.host).toBe('localhost')
+    expect(config.port).toBe(3306)
+    expect(config.database).toBe('test_db')
+    expect(config.username).toBe('test_user')
+    expect(config.password).toBe('test_password')
+  })
+
+  it('creates SQL Server config with correct port', () => {
+    const config = DatabaseFactory.createDatabaseConfig('sqlserver')
+
+    expect(config.type).toBe('sqlserver')
+    expect(config.host).toBe('localhost')
+    expect(config.port).toBe(1433)
+    expect(config.database).toBe('test_db')
+    expect(config.username).toBe('test_user')
+    expect(config.password).toBe('test_password')
+  })
+
+  it('applies overrides to database config', () => {
+    const config = DatabaseFactory.createDatabaseConfig('mysql', {
+      host: '192.168.1.100',
+      port: 3307,
+      database: 'production_db',
+      username: 'prod_user',
+      password: 'prod_password'
+    })
+
+    expect(config.type).toBe('mysql')
+    expect(config.host).toBe('192.168.1.100')
+    expect(config.port).toBe(3307)
+    expect(config.database).toBe('production_db')
+    expect(config.username).toBe('prod_user')
+    expect(config.password).toBe('prod_password')
+  })
+})