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/onboarding.service.ts

@@ -0,0 +1,46 @@
+import axios from 'axios'
+import type {
+  OnboardingRequest,
+  OnboardingResponse,
+  EmployeeStatusResponse,
+} from '../types/onboarding'
+
+const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:10181'
+
+class OnboardingService {
+  /**
+   * 員工到職
+   */
+  async onboardEmployee(request: OnboardingRequest): Promise<OnboardingResponse> {
+    const response = await axios.post<OnboardingResponse>(
+      `${API_BASE_URL}/api/v1/emp-lifecycle/onboard`,
+      request
+    )
+    return response.data
+  }
+
+  /**
+   * 查詢員工狀態
+   */
+  async getEmployeeStatus(
+    tenantId: number,
+    seqNo: number
+  ): Promise<EmployeeStatusResponse> {
+    const response = await axios.get<EmployeeStatusResponse>(
+      `${API_BASE_URL}/api/v1/emp-lifecycle/${tenantId}/${seqNo}/status`
+    )
+    return response.data
+  }
+
+  /**
+   * 員工離職
+   */
+  async offboardEmployee(tenantId: number, seqNo: number) {
+    const response = await axios.post(
+      `${API_BASE_URL}/api/v1/emp-lifecycle/${tenantId}/${seqNo}/offboard`
+    )
+    return response.data
+  }
+}
+
+export const onboardingService = new OnboardingService()