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>

app/modules/auth/services/user_service.py

@@ -0,0 +1,89 @@
+"""User service for permanent user information storage
+
+This service handles upsert operations for the users table,
+which stores display names and metadata for report generation.
+"""
+from datetime import datetime
+from typing import Optional
+from sqlalchemy.orm import Session
+from app.modules.auth.models import User
+
+
+def upsert_user(
+    db: Session,
+    user_id: str,
+    display_name: str,
+    office_location: Optional[str] = None,
+    job_title: Optional[str] = None,
+) -> User:
+    """Create or update user record with AD information
+
+    This function is called on every successful login to keep
+    user information up to date. Uses SQLAlchemy merge for
+    atomic upsert operation.
+
+    Args:
+        db: Database session
+        user_id: User email address (primary key)
+        display_name: Display name from AD API
+        office_location: Office location from AD API (optional)
+        job_title: Job title from AD API (optional)
+
+    Returns:
+        User: The created or updated user record
+    """
+    # Check if user exists
+    existing_user = db.query(User).filter(User.user_id == user_id).first()
+
+    if existing_user:
+        # Update existing user
+        existing_user.display_name = display_name
+        existing_user.office_location = office_location
+        existing_user.job_title = job_title
+        existing_user.last_login_at = datetime.utcnow()
+        db.commit()
+        db.refresh(existing_user)
+        return existing_user
+    else:
+        # Create new user
+        new_user = User(
+            user_id=user_id,
+            display_name=display_name,
+            office_location=office_location,
+            job_title=job_title,
+            last_login_at=datetime.utcnow(),
+            created_at=datetime.utcnow(),
+        )
+        db.add(new_user)
+        db.commit()
+        db.refresh(new_user)
+        return new_user
+
+
+def get_user_by_id(db: Session, user_id: str) -> Optional[User]:
+    """Get user by user_id (email)
+
+    Args:
+        db: Database session
+        user_id: User email address
+
+    Returns:
+        User or None if not found
+    """
+    return db.query(User).filter(User.user_id == user_id).first()
+
+
+def get_display_name(db: Session, user_id: str) -> str:
+    """Get display name for a user, falling back to email if not found
+
+    Args:
+        db: Database session
+        user_id: User email address
+
+    Returns:
+        Display name or email address as fallback
+    """
+    user = get_user_by_id(db, user_id)
+    if user:
+        return user.display_name
+    return user_id  # Fallback to email if user not in database