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>

backend/check_tenant_status.py

@@ -0,0 +1,51 @@
+"""
+檢查租戶初始化狀態
+"""
+import psycopg2
+
+conn = psycopg2.connect(
+    host="10.1.0.20",
+    port=5433,
+    database="hr_portal",
+    user="admin",
+    password="DC1qaz2wsx"
+)
+cur = conn.cursor()
+
+# 查詢租戶狀態
+cur.execute("""
+    SELECT id, code, name, is_initialized, initialized_at, initialized_by, status
+    FROM tenants
+    ORDER BY id;
+""")
+
+tenants = cur.fetchall()
+
+print("=== Tenants Status ===\n")
+
+for t in tenants:
+    print(f"ID: {t[0]}")
+    print(f"Code: {t[1]}")
+    print(f"Name: {t[2]}")
+    print(f"Is Initialized: {t[3]}")
+    print(f"Initialized At: {t[4]}")
+    print(f"Initialized By: {t[5]}")
+    print(f"Status: {t[6]}")
+    print("-" * 50)
+
+# 查詢系統狀態
+cur.execute("""
+    SELECT current_phase, initialization_completed, is_locked
+    FROM installation_system_status
+    WHERE id = 1;
+""")
+
+sys_status = cur.fetchone()
+if sys_status:
+    print("\n=== System Status ===\n")
+    print(f"Current Phase: {sys_status[0]}")
+    print(f"Initialization Completed: {sys_status[1]}")
+    print(f"Is Locked: {sys_status[2]}")
+
+cur.close()
+conn.close()