chore: remove obsolete files and installation packages

This commit removes several files and directories that are no longer needed:
- Deleted a PDF research paper about AI-based teacher-student service platform
- Removed the entire `af-fast-install` directory containing installation scripts and packages for various services (ddns-go, easytier, beszel-agent)
- Deleted the main installation script and bundled package archive

The removed files were part of an automated installation system that has been deprecated. This cleanup reduces repository size and removes outdated deployment scripts.

Author: minc-nice-100