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/test_system_functions_api.py

@@ -0,0 +1,92 @@
+"""
+測試 system_functions CRUD API
+"""
+import psycopg2
+import json
+
+conn = psycopg2.connect(
+    host="10.1.0.20",
+    port=5433,
+    database="hr_portal",
+    user="admin",
+    password="DC1qaz2wsx"
+)
+cur = conn.cursor()
+
+print("=" * 60)
+print("Test system_functions API")
+print("=" * 60)
+
+# Test 1: 取得所有系統功能
+print("\n[Test 1] Get all system functions")
+cur.execute("""
+    SELECT id, code, name, function_type, upper_function_id, "order"
+    FROM system_functions
+    ORDER BY "order";
+""")
+results = cur.fetchall()
+print(f"Total: {len(results)} records")
+for r in results:
+    indent = "  " if r[4] > 0 else ""
+    node_type = "NODE" if r[3] == 1 else "FUNC"
+    print(f"{indent}[{r[0]}] {r[1]} - {r[2]} ({node_type})")
+
+# Test 2: 取得樹狀結構
+print("\n[Test 2] Get tree structure")
+cur.execute("""
+    SELECT id, code, name, function_type
+    FROM system_functions
+    WHERE upper_function_id = 0
+    ORDER BY "order";
+""")
+root_nodes = cur.fetchall()
+
+for node in root_nodes:
+    node_type = "NODE" if node[3] == 1 else "FUNC"
+    print(f"[{node[0]}] {node[2]} ({node_type})")
+    
+    # 取得子功能
+    cur.execute("""
+        SELECT id, code, name, function_type
+        FROM system_functions
+        WHERE upper_function_id = %s
+        ORDER BY "order";
+    """, (node[0],))
+    children = cur.fetchall()
+    
+    for child in children:
+        child_type = "NODE" if child[3] == 1 else "FUNC"
+        print(f"  ├── [{child[0]}] {child[2]} ({child_type})")
+
+# Test 3: 篩選功能類型
+print("\n[Test 3] Filter by function_type=1 (nodes)")
+cur.execute("""
+    SELECT id, code, name
+    FROM system_functions
+    WHERE function_type = 1
+    ORDER BY "order";
+""")
+nodes = cur.fetchall()
+print(f"Total nodes: {len(nodes)}")
+for n in nodes:
+    print(f"  [{n[0]}] {n[1]} - {n[2]}")
+
+# Test 4: 篩選系統管理功能
+print("\n[Test 4] Filter by is_mana=true")
+cur.execute("""
+    SELECT id, code, name
+    FROM system_functions
+    WHERE is_mana = true
+    ORDER BY "order";
+""")
+mana_funcs = cur.fetchall()
+print(f"Total: {len(mana_funcs)} records")
+for f in mana_funcs:
+    print(f"  [{f[0]}] {f[1]} - {f[2]}")
+
+print("\n" + "=" * 60)
+print("All tests passed!")
+print("=" * 60)
+
+cur.close()
+conn.close()