Feature: tinyTikTok 数据库配置

**Is your feature request related to a problem? Please describe.**
抖音的场景比较复杂，单一数据库很难满足所有需求

**Describe the solution you'd like**
- [x] 数据库工厂模式
- [x] MySQL 配置

**Describe alternatives you've considered**
None

**Additional context**
None

Start by reviewing the repository's existing database setup and identify where a database factory and MySQL configuration would belong. Done means the requested factory pattern and MySQL configuration are implemented and usable, with the project's existing checks passing.

Written by the indexing model from the issue text.