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>

test_backend_startup.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""測試 HR Portal 後端啟動"""
+
+import sys
+import os
+
+# 添加 backend 路徑
+backend_path = os.path.join(os.path.dirname(__file__), 'backend')
+sys.path.insert(0, backend_path)
+
+print("=" * 60)
+print("HR Portal 後端啟動測試")
+print("=" * 60)
+
+try:
+    # 載入環境變數
+    print("\n[1] 載入環境變數...")
+    from dotenv import load_dotenv
+    env_path = os.path.join(backend_path, '.env')
+    load_dotenv(env_path)
+
+    print(f"  PROJECT_NAME: {os.getenv('PROJECT_NAME')}")
+    print(f"  ENVIRONMENT: {os.getenv('ENVIRONMENT')}")
+    print(f"  PORT: {os.getenv('PORT')}")
+
+    # 測試導入核心模組
+    print("\n[2] 導入核心模組...")
+
+    print("  導入 config...")
+    from app.core.config import settings
+    print(f"    [OK] Project: {settings.PROJECT_NAME}")
+    print(f"    [OK] Port: {settings.PORT}")
+
+    print("  導入 database...")
+    from app.db.session import get_engine, get_db
+    engine = get_engine()
+    print(f"    [OK] Database engine: {engine.url}")
+
+    print("  導入 models...")
+    from app.models.employee import Employee
+    from app.models.department import Department
+    from app.models.business_unit import BusinessUnit
+    print("    [OK] Models imported")
+
+    # 測試資料庫連接
+    print("\n[3] 測試資料庫連接...")
+    with engine.connect() as conn:
+        from sqlalchemy import text
+        result = conn.execute(text("SELECT 1"))
+        print("    [OK] Database connection successful")
+
+    # 測試創建 FastAPI 應用
+    print("\n[4] 測試 FastAPI 應用...")
+    from app.main import app
+    print(f"    [OK] FastAPI app created")
+    print(f"    [OK] Title: {app.title}")
+    print(f"    [OK] Version: {app.version}")
+
+    # 列出所有路由
+    print("\n[5] API 路由列表:")
+    routes = []
+    for route in app.routes:
+        if hasattr(route, 'methods') and hasattr(route, 'path'):
+            for method in route.methods:
+                if method != 'HEAD':  # 跳過 HEAD
+                    routes.append(f"    {method:7} {route.path}")
+
+    for route in sorted(set(routes)):
+        print(route)
+
+    print("\n" + "=" * 60)
+    print("後端模組載入成功!")
+    print("=" * 60)
+    print("\n提示: 使用以下命令啟動後端:")
+    print("  cd backend")
+    print("  uvicorn app.main:app --host 0.0.0.0 --port 10181 --reload")
+
+except Exception as e:
+    print(f"\n[FAIL] 測試失敗: {e}")
+    import traceback
+    traceback.print_exc()
+    sys.exit(1)