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/verify_cleanup.py

@@ -0,0 +1,58 @@
+"""
+驗證資料庫清理結果
+"""
+import psycopg2
+
+conn = psycopg2.connect(
+    host="10.1.0.20",
+    port=5433,
+    database="hr_portal",
+    user="admin",
+    password="DC1qaz2wsx"
+)
+cur = conn.cursor()
+
+print("=== Verification Report ===\n")
+
+# 檢查 tenants
+cur.execute("SELECT COUNT(*) FROM tenants;")
+count = cur.fetchone()[0]
+print(f"tenants: {count} records")
+
+# 檢查 installation_sessions
+cur.execute("SELECT COUNT(*) FROM installation_sessions;")
+count = cur.fetchone()[0]
+print(f"installation_sessions: {count} records")
+
+# 檢查 temporary_passwords
+cur.execute("SELECT COUNT(*) FROM temporary_passwords;")
+count = cur.fetchone()[0]
+print(f"temporary_passwords: {count} records")
+
+# 檢查 installation_tenant_info
+cur.execute("SELECT COUNT(*) FROM installation_tenant_info;")
+count = cur.fetchone()[0]
+print(f"installation_tenant_info: {count} records")
+
+# 檢查系統狀態
+cur.execute("SELECT current_phase, initialization_completed, is_locked FROM installation_system_status WHERE id = 1;")
+row = cur.fetchone()
+if row:
+    print(f"\nSystem Status:")
+    print(f"  Phase: {row[0]}")
+    print(f"  Initialization Completed: {row[1]}")
+    print(f"  Is Locked: {row[2]}")
+
+# 檢查序列值
+cur.execute("SELECT last_value FROM tenants_id_seq;")
+seq_val = cur.fetchone()[0]
+print(f"\ntenants_id_seq: {seq_val}")
+
+cur.execute("SELECT last_value FROM installation_sessions_id_seq;")
+seq_val = cur.fetchone()[0]
+print(f"installation_sessions_id_seq: {seq_val}")
+
+print("\n=== Ready for initialization ===")
+
+cur.close()
+conn.close()