fix: avoid duplicate release attempts

[mcollina]

The release workflow currently excludes the package's exact release tag before deciding whether to publish, causing unrelated package.json changes to queue duplicate releases. Look up the exact tag instead, return the version only when that tag does not exist, and propagate other API failures.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.47%. Comparing base (c32ea13) to head (f307254).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5745      +/-   ##
==========================================
+ Coverage   93.46%   93.47%   +0.01%     
==========================================
  Files         110      110              
  Lines       38934    38939       +5     
==========================================
+ Hits        36389    36398       +9     
+ Misses       2545     2541       -4     

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