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/batch/base.py

@@ -0,0 +1,59 @@
+"""
+批次作業基礎工具
+提供 log_batch_execution 等共用函式
+"""
+import logging
+from datetime import datetime
+from typing import Optional
+
+logger = logging.getLogger(__name__)
+
+
+def log_batch_execution(
+    batch_name: str,
+    status: str,
+    message: Optional[str] = None,
+    started_at: Optional[datetime] = None,
+    finished_at: Optional[datetime] = None,
+) -> None:
+    """
+    記錄批次執行日誌到資料庫
+
+    Args:
+        batch_name: 批次名稱
+        status: 執行狀態 (success/failed/warning)
+        message: 執行訊息
+        started_at: 開始時間 (若未提供則使用 finished_at)
+        finished_at: 完成時間 (若未提供則使用現在)
+    """
+    from app.db.session import get_db
+    from app.models.batch_log import BatchLog
+
+    now = datetime.utcnow()
+    finished = finished_at or now
+    started = started_at or finished
+
+    duration = None
+    if started and finished:
+        duration = int((finished - started).total_seconds())
+
+    try:
+        db = next(get_db())
+        log_entry = BatchLog(
+            batch_name=batch_name,
+            status=status,
+            message=message,
+            started_at=started,
+            finished_at=finished,
+            duration_seconds=duration,
+        )
+        db.add(log_entry)
+        db.commit()
+        logger.info(f"[{batch_name}] 批次執行記錄已寫入: {status}")
+    except Exception as e:
+        logger.error(f"[{batch_name}] 寫入批次日誌失敗: {e}")
+    finally:
+        try:
+            db.close()
+        except Exception:
+            pass