# Change: Add Document Processing API

## Why

DocProcesser needs a FastAPI backend to accept images (via URL or base64) and convert them to LaTeX/Markdown/MathML, plus a markdown-to-DOCX conversion endpoint. This establishes the core functionality of the project.

## What Changes

- **BREAKING**: Initial project setup (new FastAPI project structure)
- Add image-to-OCR API endpoint (`POST /doc_process/v1/image/ocr`)
  - Accept `image_url` or `image_base64` input
  - Preprocess with OpenCV (30% whitespace padding)
  - Use DocLayout-YOLO for layout detection
  - Route to PaddleOCR-VL (with PP-DocLayoutV2) for text/formula recognition
  - Exists `plain_text` element, use PP-DocLayoutV2 to recognize the image as mixed_recognition , otherwise directly PaddleOCR-VL API combined with prompt Formula Recognition as formula_recognition.
  - Refrence markdown_2_docx code convert the markdown to latex, mathml for mixed_recognition, convert the latex to markdown, mathml for formula_recognition
  - Return LaTeX, Markdown, and MathML outputs
- Add markdown-to-DOCX API endpoint (`POST /doc_process/v1/convert/docx`)
  - Accept markdown content
  - Refrence markdown_2_docx library for conversion, the address is http://github.com/YogeLiu/markdown_2_docxdd.
  - Return DOCX file
- Add Dockerfile for GPU-enabled deployment (RTX 5080, port 8053)

## Impact

- Affected specs: `image-ocr`, `markdown-docx`
- Affected code: New project structure under `app/`
- External dependencies:
  - DocLayout-YOLO (pre-downloaded model, not fetched in container)
  - PaddleOCR-VL with vLLM backend (external service at localhost:8080)
  - markdown_2_docx library