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>

frontend/test-redis.js

@@ -0,0 +1,46 @@
+/**
+ * Test Redis Connection and Check Session Keys
+ */
+const Redis = require('ioredis')
+
+const redis = new Redis({
+  host: '10.1.0.20',
+  port: 6379,
+  password: '!DC1qaz2wsx',
+  db: 0,
+})
+
+async function testRedis() {
+  try {
+    console.log('Testing Redis connection...')
+
+    // Test connection
+    const pong = await redis.ping()
+    console.log('✅ Redis PING:', pong)
+
+    // List all nextauth keys
+    const keys = await redis.keys('nextauth:*')
+    console.log('\n📋 NextAuth session keys:', keys)
+    console.log('Total keys:', keys.length)
+
+    // Show first key content if exists
+    if (keys.length > 0) {
+      const firstKey = keys[0]
+      const value = await redis.get(firstKey)
+      console.log(`\n📄 Content of ${firstKey}:`)
+      console.log(value)
+
+      const ttl = await redis.ttl(firstKey)
+      console.log(`\n⏰ TTL: ${ttl} seconds`)
+    } else {
+      console.log('\n⚠️  No session keys found!')
+    }
+
+  } catch (error) {
+    console.error('❌ Redis error:', error)
+  } finally {
+    redis.disconnect()
+  }
+}
+
+testRedis()