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/batch_log.py

@@ -0,0 +1,31 @@
+"""
+批次執行日誌 Model
+記錄所有批次作業的執行結果
+"""
+from datetime import datetime
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text
+
+from app.db.base import Base
+
+
+class BatchLog(Base):
+    """批次執行日誌表"""
+
+    __tablename__ = "tenant_batch_logs"
+
+    id = Column(Integer, primary_key=True, index=True)
+    batch_name = Column(String(100), nullable=False, index=True, comment="批次名稱")
+    status = Column(String(20), nullable=False, comment="執行狀態: success/failed/warning")
+    message = Column(Text, comment="執行訊息或錯誤詳情")
+    started_at = Column(DateTime, nullable=False, default=datetime.utcnow, index=True, comment="開始時間")
+    finished_at = Column(DateTime, comment="完成時間")
+    duration_seconds = Column(Integer, comment="執行時間 (秒)")
+
+    # 通用欄位
+    is_active = Column(Boolean, default=True, nullable=False, comment="是否啟用")
+    edit_by = Column(String(100), nullable=True, comment="最後編輯者")
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False, comment="建立時間")
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow, nullable=False, comment="更新時間")
+
+    def __repr__(self):
+        return f"<BatchLog {self.batch_name} [{self.status}] @ {self.started_at}>"