src: collapse local var scope in loop

[mertcanaltin]

This change narrows the scope of local variables to within the loop to improve code clarity and reduce the risk of variable misuse. Although purely stylistic, it helps with maintainability.

[nodejs-github-bot]

Review requested:

• @nodejs/config

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.23%. Comparing base (af75d04) to head (426d089).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #57626      +/-   ##
==========================================
- Coverage   90.23%   90.23%   -0.01%     
==========================================
  Files         630      630              
  Lines      185055   185055              
  Branches    36221    36223       +2     
==========================================
- Hits       166984   166976       -8     
+ Misses      11043    11041       -2     
- Partials     7028     7038      +10     

Files with missing lines	Coverage Δ
src/node_dotenv.cc	85.71% <100.00%> (ø)

... and 19 files with indirect coverage changes

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[addaleax]

There's no harm in this, but ideally the commit message would describe the motivation for this change as well, esp. since it is a purely stylistic one

[mertcanaltin]

There's no harm in this, but ideally the commit message would describe the motivation for this change as well, esp. since it is a purely stylistic one

Thanks, I edited