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/app/models/__init__.py

@@ -0,0 +1,84 @@
+"""
+Models 模組
+匯出所有資料庫模型
+"""
+# 多租戶核心模型
+from app.models.tenant import Tenant, TenantStatus
+from app.models.system_function_cache import SystemFunctionCache
+from app.models.system_function import SystemFunction
+from app.models.personal_service import PersonalService
+
+# HR 組織架構
+from app.models.department import Department
+from app.models.department_member import DepartmentMember
+
+# HR 員工模型
+from app.models.employee import Employee, EmployeeStatus
+from app.models.emp_resume import EmpResume
+from app.models.emp_setting import EmpSetting
+from app.models.emp_personal_service_setting import EmpPersonalServiceSetting
+
+# RBAC 權限系統
+from app.models.role import UserRole, RoleRight, UserRoleAssignment
+
+# 其他業務模型
+from app.models.email_account import EmailAccount
+from app.models.network_drive import NetworkDrive
+from app.models.permission import Permission
+from app.models.audit_log import AuditLog
+from app.models.batch_log import BatchLog
+
+# 初始化系統
+from app.models.installation import (
+    InstallationSession,
+    InstallationChecklistItem,
+    InstallationChecklistResult,
+    InstallationStep,
+    InstallationLog,
+    InstallationTenantInfo,
+    InstallationDepartmentSetup,
+    TemporaryPassword,
+    InstallationAccessLog,
+    InstallationEnvironmentConfig,
+    InstallationSystemStatus
+)
+
+__all__ = [
+    # 多租戶核心
+    "Tenant",
+    "TenantStatus",
+    "SystemFunctionCache",
+    "SystemFunction",
+    "PersonalService",
+    # 組織架構
+    "Department",
+    "DepartmentMember",
+    # 員工模型
+    "Employee",
+    "EmployeeStatus",
+    "EmpResume",
+    "EmpSetting",
+    "EmpPersonalServiceSetting",
+    # RBAC 權限系統
+    "UserRole",
+    "RoleRight",
+    "UserRoleAssignment",
+    # 其他業務
+    "EmailAccount",
+    "NetworkDrive",
+    "Permission",
+    "AuditLog",
+    "BatchLog",
+    # 初始化系統
+    "InstallationSession",
+    "InstallationChecklistItem",
+    "InstallationChecklistResult",
+    "InstallationStep",
+    "InstallationLog",
+    "InstallationTenantInfo",
+    "InstallationDepartmentSetup",
+    "TemporaryPassword",
+    "InstallationAccessLog",
+    "InstallationEnvironmentConfig",
+    "InstallationSystemStatus",
+]