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/schemas/audit_log.py

@@ -0,0 +1,107 @@
+"""
+審計日誌 Schemas
+"""
+from datetime import datetime
+from typing import Optional, Dict, Any
+from pydantic import Field, ConfigDict
+
+from app.schemas.base import BaseSchema
+
+
+class AuditLogBase(BaseSchema):
+    """審計日誌基礎 Schema"""
+
+    action: str = Field(..., max_length=50, description="操作類型 (create/update/delete/login)")
+    resource_type: str = Field(..., max_length=50, description="資源類型 (employee/identity/department)")
+    resource_id: Optional[int] = Field(None, description="資源 ID")
+    performed_by: str = Field(..., max_length=100, description="操作者 SSO 帳號")
+    details: Optional[Dict[str, Any]] = Field(None, description="詳細變更內容")
+    ip_address: Optional[str] = Field(None, max_length=45, description="IP 位址")
+
+
+class AuditLogCreate(AuditLogBase):
+    """創建審計日誌 Schema"""
+
+    model_config = ConfigDict(
+        json_schema_extra={
+            "example": {
+                "action": "create",
+                "resource_type": "employee",
+                "resource_id": 1,
+                "performed_by": "porsche.chen@lab.taipei",
+                "details": {
+                    "employee_id": "EMP001",
+                    "legal_name": "陳保時",
+                    "username_base": "porsche.chen"
+                },
+                "ip_address": "10.1.0.245"
+            }
+        }
+    )
+
+
+class AuditLogInDB(AuditLogBase):
+    """資料庫中的審計日誌 Schema"""
+
+    id: int
+    performed_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AuditLogResponse(AuditLogInDB):
+    """審計日誌響應 Schema"""
+
+    model_config = ConfigDict(
+        json_schema_extra={
+            "example": {
+                "id": 1,
+                "action": "create",
+                "resource_type": "employee",
+                "resource_id": 1,
+                "performed_by": "porsche.chen@lab.taipei",
+                "performed_at": "2020-01-01T12:00:00",
+                "details": {
+                    "employee_id": "EMP001",
+                    "legal_name": "陳保時",
+                    "username_base": "porsche.chen"
+                },
+                "ip_address": "10.1.0.245"
+            }
+        }
+    )
+
+
+class AuditLogListItem(BaseSchema):
+    """審計日誌列表項 Schema"""
+
+    id: int
+    action: str
+    resource_type: str
+    resource_id: Optional[int] = None
+    performed_by: str
+    performed_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AuditLogFilter(BaseSchema):
+    """審計日誌篩選參數"""
+
+    action: Optional[str] = None
+    resource_type: Optional[str] = None
+    resource_id: Optional[int] = None
+    performed_by: Optional[str] = None
+    start_date: Optional[datetime] = None
+    end_date: Optional[datetime] = None
+
+    model_config = ConfigDict(
+        json_schema_extra={
+            "example": {
+                "action": "create",
+                "resource_type": "employee",
+                "start_date": "2020-01-01T00:00:00",
+                "end_date": "2020-12-31T23:59:59"
+            }
+        }
+    )