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>

scripts/setup-database.ps1

@@ -0,0 +1,102 @@
+# ====================================
+# HR Portal - 資料庫設定腳本 (PowerShell)
+# ====================================
+
+Write-Host "=== HR Portal 資料庫設定 ===" -ForegroundColor Cyan
+Write-Host ""
+
+# 設定變數
+$DB_HOST = "10.1.0.254"
+$DB_NAME = "hr_portal"
+$DB_USER = "hr_user"
+$DB_PASSWORD = "hr_password_change_me"  # 請修改為強密碼
+
+Write-Host "連接到 PostgreSQL..." -ForegroundColor Yellow
+Write-Host ""
+
+# 檢查 psql 是否可用
+$psqlAvailable = Get-Command psql -ErrorAction SilentlyContinue
+
+if (-not $psqlAvailable) {
+    Write-Host "錯誤: 找不到 psql 命令" -ForegroundColor Red
+    Write-Host "請確認 PostgreSQL 客戶端已安裝" -ForegroundColor Red
+    Write-Host "或使用 Docker 方式執行" -ForegroundColor Yellow
+    exit 1
+}
+
+try {
+    # 1. 創建資料庫用戶
+    Write-Host "1. 創建資料庫用戶: $DB_USER" -ForegroundColor Green
+
+    $createUserSQL = @"
+DO `$`$
+BEGIN
+   IF NOT EXISTS (SELECT FROM pg_user WHERE usename = '$DB_USER') THEN
+      CREATE USER $DB_USER WITH PASSWORD '$DB_PASSWORD';
+      RAISE NOTICE 'User $DB_USER created';
+   ELSE
+      RAISE NOTICE 'User $DB_USER already exists';
+   END IF;
+END
+`$`$;
+"@
+
+    $createUserSQL | psql -h $DB_HOST -U postgres -w
+
+    Write-Host ""
+
+    # 2. 創建資料庫
+    Write-Host "2. 創建資料庫: $DB_NAME" -ForegroundColor Green
+
+    $createDbSQL = @"
+SELECT 'CREATE DATABASE $DB_NAME OWNER $DB_USER'
+WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '$DB_NAME')\gexec
+"@
+
+    $createDbSQL | psql -h $DB_HOST -U postgres -w
+
+    Write-Host ""
+
+    # 3. 授予權限
+    Write-Host "3. 授予權限" -ForegroundColor Green
+
+    $grantSQL = @"
+GRANT ALL PRIVILEGES ON DATABASE $DB_NAME TO $DB_USER;
+GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO $DB_USER;
+GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA public TO $DB_USER;
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON TABLES TO $DB_USER;
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON SEQUENCES TO $DB_USER;
+"@
+
+    $grantSQL | psql -h $DB_HOST -U postgres -d $DB_NAME -w
+
+    Write-Host ""
+
+    # 4. 執行 Schema 初始化
+    Write-Host "4. 執行 Schema 初始化" -ForegroundColor Green
+
+    $schemaFile = Join-Path $PSScriptRoot "init-db.sql"
+
+    if (Test-Path $schemaFile) {
+        Get-Content $schemaFile | psql -h $DB_HOST -U $DB_USER -d $DB_NAME
+    } else {
+        Write-Host "警告: 找不到 init-db.sql" -ForegroundColor Yellow
+    }
+
+    Write-Host ""
+    Write-Host "✅ 資料庫設定完成!" -ForegroundColor Green
+    Write-Host ""
+    Write-Host "資料庫連接資訊:" -ForegroundColor Cyan
+    Write-Host "  Host: $DB_HOST"
+    Write-Host "  Database: $DB_NAME"
+    Write-Host "  User: $DB_USER"
+    Write-Host "  Password: $DB_PASSWORD"
+    Write-Host ""
+    Write-Host "DATABASE_URL: postgresql://${DB_USER}:${DB_PASSWORD}@${DB_HOST}:5432/${DB_NAME}" -ForegroundColor Yellow
+    Write-Host ""
+    Write-Host "請將上述 DATABASE_URL 複製到 backend/.env 檔案中" -ForegroundColor Cyan
+
+} catch {
+    Write-Host "錯誤: $_" -ForegroundColor Red
+    exit 1
+}