refactor: 拆分 models 和 handlers 避免循环导入

[he0119]

这两个东西不应该混在一起。

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.77%. Comparing base (a02ad0b) to head (2c68211).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #323      +/-   ##
==========================================
- Coverage   92.77%   92.77%   -0.01%     
==========================================
  Files          40       41       +1     
  Lines        2202     2201       -1     
==========================================
- Hits         2043     2042       -1     
  Misses        159      159              

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