feat: HR Portal - Complete Multi-Tenant System with Redis Session Storage

Major Features:
- ✅ Multi-tenant architecture (tenant isolation)
- ✅ Employee CRUD with lifecycle management (onboarding/offboarding)
- ✅ Department tree structure with email domain management
- ✅ Company info management (single-record editing)
- ✅ System functions CRUD (permission management)
- ✅ Email account management (multi-account per employee)
- ✅ Keycloak SSO integration (auth.lab.taipei)
- ✅ Redis session storage (10.1.0.254:6379)
  - Solves Cookie 4KB limitation
  - Cross-system session sharing
  - Sliding expiration (8 hours)
  - Automatic token refresh

Technical Stack:
Backend:
- FastAPI + SQLAlchemy
- PostgreSQL 16 (10.1.0.20:5433)
- Keycloak Admin API integration
- Docker Mailserver integration (SSH)
- Alembic migrations

Frontend:
- Next.js 14 (App Router)
- NextAuth 4 with Keycloak Provider
- Redis session storage (ioredis)
- Tailwind CSS

Infrastructure:
- Redis 7 (10.1.0.254:6379) - Session + Cache
- Keycloak 26.1.0 (auth.lab.taipei)
- Docker Mailserver (10.1.0.254)

Architecture Highlights:
- Session管理由 Keycloak + Redis 統一控制
- 支援多系統 (HR/WebMail/Calendar/Drive/Office) 共享 session
- Token 自動刷新,異質服務整合
- 未來可無縫遷移到雲端

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

frontend/services/__tests__/tenant.service.test.ts

@@ -0,0 +1,141 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest'
+import axios from 'axios'
+import { tenantService } from '../tenant.service'
+import type { Tenant, TenantUpdateRequest, TenantUpdateResponse } from '../../types/tenant'
+
+// Mock axios
+vi.mock('axios', () => ({
+  default: {
+    get: vi.fn(),
+    put: vi.fn(),
+  },
+}))
+
+const mockedAxios = axios as unknown as {
+  get: ReturnType<typeof vi.fn>
+  put: ReturnType<typeof vi.fn>
+}
+
+describe('TenantService', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  describe('getTenant', () => {
+    it('should fetch tenant information successfully', async () => {
+      // Arrange
+      const tenantId = 1
+      const mockTenant: Tenant = {
+        id: 1,
+        code: 'PWD',
+        name: 'Porsche World',
+        name_eng: 'Porsche World Co., Ltd.',
+        tax_id: '12345678',
+        prefix: 'PWD',
+        tel: '02-1234-5678',
+        add: '台北市信義區...',
+        url: 'https://porscheworld.tw',
+        plan_id: 'starter',
+        max_users: 50,
+        storage_quota_gb: 1000,
+        status: 'active',
+        is_sysmana: false,
+        is_active: true,
+        created_at: '2026-01-01T00:00:00',
+        updated_at: '2026-02-21T00:00:00',
+      }
+
+      mockedAxios.get.mockResolvedValueOnce({ data: mockTenant })
+
+      // Act
+      const result = await tenantService.getTenant(tenantId)
+
+      // Assert
+      expect(mockedAxios.get).toHaveBeenCalledWith(
+        `http://localhost:10181/api/v1/tenants/${tenantId}`
+      )
+      expect(result).toEqual(mockTenant)
+    })
+
+    it('should throw error when tenant not found', async () => {
+      // Arrange
+      const tenantId = 999
+      mockedAxios.get.mockRejectedValueOnce({
+        response: {
+          data: { detail: 'Tenant not found' },
+          status: 404,
+        },
+      })
+
+      // Act & Assert
+      await expect(tenantService.getTenant(tenantId)).rejects.toThrow()
+    })
+  })
+
+  describe('updateTenant', () => {
+    it('should update tenant information successfully', async () => {
+      // Arrange
+      const tenantId = 1
+      const updateData: TenantUpdateRequest = {
+        name: 'Porsche World Updated',
+        tax_id: '87654321',
+        tel: '02-8765-4321',
+        add: '台北市大安區...',
+        url: 'https://newporscheworld.tw',
+      }
+
+      const mockResponse: TenantUpdateResponse = {
+        message: 'Tenant updated successfully',
+        tenant: {
+          id: 1,
+          code: 'PWD',
+          name: 'Porsche World Updated',
+          name_eng: 'Porsche World Co., Ltd.',
+          tax_id: '87654321',
+          prefix: 'PWD',
+          tel: '02-8765-4321',
+          add: '台北市大安區...',
+          url: 'https://newporscheworld.tw',
+          plan_id: 'starter',
+          max_users: 50,
+          storage_quota_gb: 1000,
+          status: 'active',
+          is_sysmana: false,
+          is_active: true,
+          created_at: '2026-01-01T00:00:00',
+          updated_at: '2026-02-21T10:00:00',
+        },
+      }
+
+      mockedAxios.put.mockResolvedValueOnce({ data: mockResponse })
+
+      // Act
+      const result = await tenantService.updateTenant(tenantId, updateData)
+
+      // Assert
+      expect(mockedAxios.put).toHaveBeenCalledWith(
+        `http://localhost:10181/api/v1/tenants/${tenantId}`,
+        updateData
+      )
+      expect(result).toEqual(mockResponse)
+    })
+
+    it('should throw error when update fails', async () => {
+      // Arrange
+      const tenantId = 1
+      const updateData: TenantUpdateRequest = {
+        name: 'Test',
+      }
+
+      mockedAxios.put.mockRejectedValueOnce({
+        response: {
+          data: { detail: 'Update failed' },
+          status: 400,
+        },
+      })
+
+      // Act & Assert
+      await expect(tenantService.updateTenant(tenantId, updateData)).rejects.toThrow()
+    })
+  })
+})