[fix][infra]: makefile nginx-volume name

[lsy357]

What type of PR is this?

fix

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[CozeLoop]

Code Review Summary

I have completed a comprehensive review of PR #185. This is a well-executed infrastructure fix that addresses Makefile variable expansion issues and removes an unwanted backup file.

Key Findings:

• ✅ Correct Fix: The shell variable syntax correction from $${VAR} to ${VAR} properly fixes variable expansion
• ✅ Consistent Implementation: The fix is applied consistently across all three occurrences
• ✅ Good Cleanup: Removal of .backup file improves repository hygiene
• 💡 Minor Enhancement: Consider adding documentation for the new variable

Overall Assessment:

This PR demonstrates good attention to detail and follows best practices for infrastructure maintenance. The changes are minimal, focused, and address the stated issue effectively.

Recommendation: APPROVE with minor suggestions for documentation enhancement.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
- Coverage   58.82%   58.81%   -0.01%     
==========================================
  Files         512      512              
  Lines       53303    53303              
==========================================
- Hits        31354    31351       -3     
- Misses      19569    19571       +2     
- Partials     2380     2381       +1     

Flag	Coverage Δ
unittests	58.81% <ø> (-0.01%)	⬇️

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