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/employee.py

@@ -0,0 +1,120 @@
+"""
+員工 Schemas
+"""
+from datetime import date, datetime
+from typing import Optional, List
+from pydantic import BaseModel, Field, EmailStr, ConfigDict
+
+from app.schemas.base import BaseSchema, TimestampSchema
+from app.models.employee import EmployeeStatus
+
+
+class EmployeeBase(BaseSchema):
+    """員工基礎 Schema"""
+
+    username_base: str = Field(..., min_length=3, max_length=50, description="基礎帳號名稱 (全公司唯一)")
+    legal_name: str = Field(..., min_length=2, max_length=100, description="法定姓名")
+    english_name: Optional[str] = Field(None, max_length=100, description="英文名稱")
+    phone: Optional[str] = Field(None, max_length=20, description="電話")
+    mobile: Optional[str] = Field(None, max_length=20, description="手機")
+
+
+class EmployeeCreate(EmployeeBase):
+    """創建員工 Schema (多層部門架構: department_id 指向任何層部門)"""
+
+    hire_date: date = Field(..., description="到職日期")
+
+    # 組織資訊 (新多層部門架構)
+    department_id: Optional[int] = Field(None, description="部門 ID (任何層級，選填)")
+    job_title: str = Field(..., min_length=2, max_length=100, description="職稱")
+    email_quota_mb: int = Field(5120, gt=0, description="郵件配額 (MB)，預設 5120")
+
+    model_config = ConfigDict(
+        json_schema_extra={
+            "example": {
+                "username_base": "porsche.chen",
+                "legal_name": "陳保時",
+                "english_name": "Porsche Chen",
+                "phone": "02-1234-5678",
+                "mobile": "0912-345-678",
+                "hire_date": "2020-01-01",
+                "department_id": 2,
+                "job_title": "軟體工程師",
+                "email_quota_mb": 5120
+            }
+        }
+    )
+
+
+class EmployeeUpdate(BaseSchema):
+    """更新員工 Schema"""
+
+    legal_name: Optional[str] = Field(None, min_length=2, max_length=100)
+    english_name: Optional[str] = Field(None, max_length=100)
+    phone: Optional[str] = Field(None, max_length=20)
+    mobile: Optional[str] = Field(None, max_length=20)
+    status: Optional[EmployeeStatus] = None
+
+
+class EmployeeInDB(EmployeeBase, TimestampSchema):
+    """資料庫中的員工 Schema"""
+
+    id: int
+    employee_id: str = Field(..., description="員工編號 (EMP001)")
+    hire_date: date
+    status: EmployeeStatus
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class EmployeeResponse(EmployeeInDB):
+    """員工響應 Schema (多部門成員架構)"""
+
+    has_network_drive: Optional[bool] = Field(None, description="是否有 NAS 帳號")
+    department_count: Optional[int] = Field(None, description="所屬部門數量")
+
+    model_config = ConfigDict(
+        from_attributes=True,
+        json_schema_extra={
+            "example": {
+                "id": 1,
+                "employee_id": "EMP001",
+                "username_base": "porsche.chen",
+                "legal_name": "陳保時",
+                "english_name": "Porsche Chen",
+                "phone": "02-1234-5678",
+                "mobile": "0912-345-678",
+                "hire_date": "2020-01-01",
+                "status": "active",
+                "has_network_drive": True,
+                "department_count": 2,
+                "created_at": "2020-01-01T00:00:00",
+                "updated_at": "2020-01-01T00:00:00"
+            }
+        }
+    )
+
+
+class EmployeeListItem(BaseSchema):
+    """員工列表項 Schema (簡化版，多部門成員架構)"""
+
+    id: int
+    employee_id: str
+    username_base: str
+    legal_name: str
+    english_name: Optional[str] = None
+    status: EmployeeStatus
+    hire_date: date
+
+    # 主要部門資訊 (從 department_memberships 取得)
+    primary_department: Optional[str] = Field(None, description="主要部門名稱")
+    primary_job_title: Optional[str] = Field(None, description="職稱")
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class EmployeeDetail(EmployeeInDB):
+    """員工詳情 Schema (包含完整關聯資料)"""
+
+    # 將在後續添加 identities 和 network_drive
+    pass