✨ [Feature] add content extractor

## 📝 Description
add content extractor

## 📌 Background / Necessity
Why is this feature needed? What problem does it solve?

## 📋 Detailed Requirements
- [x] docx extractor
- [x] pdf extractor
- [x] txt extractor

## 📷 References (Optional)
Attach related images, links, or documents if available.

## 🗒️ Additional Notes
Add any other context or information here.