fix: resolve swagger 500 error from swag v1/v2 registry mismatch

[JoonsooWon]

This is a very minor fix
The docs.json endpoint returned HTTP 500 because swaggo/swag v2 is incompatible with gin-swagger v1.

Changes

• Pin swaggo/swag to v1.16.x in go.mod and regenrate docs
• Pin the swag cli in scripts/swag-gen.sh to prevent future drift

before

after

related issue - #1260

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.60%. Comparing base (013dbdd) to head (deb8dbb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1265      +/-   ##
==========================================
+ Coverage   90.56%   90.60%   +0.04%     
==========================================
  Files         349      349              
  Lines       26429    26429              
==========================================
+ Hits        23935    23946      +11     
+ Misses       1693     1684       -9     
+ Partials      801      799       -2     

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