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/scripts/update_func_17.sql

@@ -0,0 +1,18 @@
+-- 修正 ID=17 「公司資料維護」功能代碼
+-- 日期: 2026-02-23
+-- 說明: 僅修正 code 和 module_code 為 company-info,與前端路徑保持一致
+
+-- 1. 查看當前設定
+SELECT id, code, module_code, name FROM system_functions WHERE id = 17;
+
+-- 2. 修正為 company-info
+UPDATE system_functions
+SET
+    code = 'company-info',
+    module_code = 'company-info',
+    module_functions = '["View", "Update"]'::jsonb,
+    edit_by = 1
+WHERE id = 17;
+
+-- 3. 確認修正結果
+SELECT id, code, module_code, name, module_functions FROM system_functions WHERE id = 17;