feat: Add AI report generation with DIFY integration

- Add Users table for display name resolution from AD authentication
- Integrate DIFY AI service for report content generation
- Create docx assembly service with image embedding from MinIO
- Add REST API endpoints for report generation and download
- Add WebSocket notifications for generation progress
- Add frontend UI with progress modal and download functionality
- Add integration tests for report generation flow

Report sections (Traditional Chinese):
- 事件摘要 (Summary)
- 時間軸 (Timeline)
- 參與人員 (Participants)
- 處理過程 (Resolution Process)
- 目前狀態 (Current Status)
- 最終處置結果 (Final Resolution)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_user_service.py

@@ -0,0 +1,164 @@
+"""Unit tests for user service
+
+Tests for the users table and upsert operations used in report generation.
+"""
+import pytest
+from datetime import datetime, timedelta
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from app.core.database import Base
+from app.modules.auth.models import User
+from app.modules.auth.services.user_service import upsert_user, get_user_by_id, get_display_name
+
+
+# Create in-memory SQLite database for testing
+@pytest.fixture
+def db_session():
+    """Create a fresh database session for each test"""
+    engine = create_engine("sqlite:///:memory:")
+    Base.metadata.create_all(bind=engine)
+    SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()
+
+
+class TestUpsertUser:
+    """Tests for upsert_user function"""
+
+    def test_create_new_user(self, db_session):
+        """Test creating a new user record"""
+        user = upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User 測試用戶",
+            office_location="Taipei",
+            job_title="Engineer",
+        )
+
+        assert user.user_id == "test@example.com"
+        assert user.display_name == "Test User 測試用戶"
+        assert user.office_location == "Taipei"
+        assert user.job_title == "Engineer"
+        assert user.last_login_at is not None
+        assert user.created_at is not None
+
+    def test_update_existing_user(self, db_session):
+        """Test updating an existing user record"""
+        # Create initial user
+        user1 = upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Original Name",
+            office_location="Taipei",
+            job_title="Junior Engineer",
+        )
+        original_created_at = user1.created_at
+        original_last_login = user1.last_login_at
+
+        # Wait a tiny bit to ensure timestamp difference
+        import time
+        time.sleep(0.01)
+
+        # Update same user
+        user2 = upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Updated Name 更新名稱",
+            office_location="Kaohsiung",
+            job_title="Senior Engineer",
+        )
+
+        # Verify update
+        assert user2.user_id == "test@example.com"
+        assert user2.display_name == "Updated Name 更新名稱"
+        assert user2.office_location == "Kaohsiung"
+        assert user2.job_title == "Senior Engineer"
+        # created_at should be preserved
+        assert user2.created_at == original_created_at
+        # last_login_at should be updated
+        assert user2.last_login_at >= original_last_login
+
+    def test_upsert_with_null_optional_fields(self, db_session):
+        """Test upsert with null office_location and job_title"""
+        user = upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User",
+            office_location=None,
+            job_title=None,
+        )
+
+        assert user.office_location is None
+        assert user.job_title is None
+
+    def test_update_clears_optional_fields(self, db_session):
+        """Test that updating with None clears optional fields"""
+        # Create with values
+        upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User",
+            office_location="Taipei",
+            job_title="Engineer",
+        )
+
+        # Update with None
+        user = upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User",
+            office_location=None,
+            job_title=None,
+        )
+
+        assert user.office_location is None
+        assert user.job_title is None
+
+
+class TestGetUserById:
+    """Tests for get_user_by_id function"""
+
+    def test_get_existing_user(self, db_session):
+        """Test getting an existing user"""
+        upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User",
+        )
+
+        user = get_user_by_id(db_session, "test@example.com")
+
+        assert user is not None
+        assert user.display_name == "Test User"
+
+    def test_get_nonexistent_user(self, db_session):
+        """Test getting a user that doesn't exist"""
+        user = get_user_by_id(db_session, "nonexistent@example.com")
+
+        assert user is None
+
+
+class TestGetDisplayName:
+    """Tests for get_display_name function"""
+
+    def test_get_display_name_existing_user(self, db_session):
+        """Test getting display name for existing user"""
+        upsert_user(
+            db=db_session,
+            user_id="test@example.com",
+            display_name="Test User 測試用戶",
+        )
+
+        name = get_display_name(db_session, "test@example.com")
+
+        assert name == "Test User 測試用戶"
+
+    def test_get_display_name_nonexistent_user(self, db_session):
+        """Test fallback to email for nonexistent user"""
+        name = get_display_name(db_session, "unknown@example.com")
+
+        # Should return email as fallback
+        assert name == "unknown@example.com"