Feature: tinyTikTok 仓库层

**Is your feature request related to a problem? Please describe.**
处理数据，和mysql、redis等crud

**Describe the solution you'd like**
- [x] comment
- [x] favorite
- [x] feed
- [x] publish
- [x] user

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.

Start by locating the repository or data-access layer and its MySQL and Redis entry points. Review how CRUD is expected to support comments, favorites, feeds, publishing, and users; done should mean each listed area has the required repository operations and the relevant checks pass.

Written by the indexing model from the issue text.