🧪 Add comprehensive edge case tests for obfuscate_string

[ffalcinelli]

Added unit tests for the obfuscate_string utility function to ensure reliable masking of sensitive data across various string types, including short strings, multi-byte Unicode characters (emojis), and whitespace. This addresses the testing gap for boundary conditions and non-ASCII character handling.

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PR created automatically by Jules for task 17652285989970506663 started by @ffalcinelli

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.27%. Comparing base (28d41eb) to head (9dd925b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #55   +/-   ##
=======================================
  Coverage   83.27%   83.27%           
=======================================
  Files          11       11           
  Lines        2296     2296           
=======================================
  Hits         1912     1912           
  Misses        384      384           

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