🧪 [testing improvement create_spinner] Add property assertions to test_create_spinner

[ffalcinelli]

🎯 What: The testing gap addressed
The create_spinner UI helper function in src/utils/ui.rs had an incomplete test (test_create_spinner) that only asserted the generated message. It did not verify other expected properties of a spinner progress bar.

📊 Coverage: What scenarios are now tested
The test now asserts the following properties of the indicatif::ProgressBar configured as a spinner:

• The message correctly matches the input string.
• The length is None (as expected for a spinner).
• The position is 0 upon initialization.
• The is_finished state is false.

✨ Result: The improvement in test coverage
The robustness of the UI utility testing is improved by ensuring that the spinner configuration relies on correct default properties beyond just the initial message, providing better confidence against unintended changes in the builder.

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PR created automatically by Jules for task 9056026470005718930 started by @ffalcinelli

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.54%. Comparing base (596135a) to head (01aa196).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #144   +/-   ##
=======================================
  Coverage   92.54%   92.54%           
=======================================
  Files          27       27           
  Lines        2227     2227           
=======================================
  Hits         2061     2061           
  Misses        166      166           

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