refactor: use mock_timeit utility in categorical timeit test

[ovodela]

Summary

• Replaces the manual time.time patch (hardcoded float array with .pop()) in test_timeit_profile with the shared test_utils.mock_timeit() context manager
• This makes the test consistent with other timeit tests in the same file (lines 940, 1004) and across the codebase
• Removes the now-unused from unittest.mock import patch import
• No behavioral change: the expected timing values (1.0 after first update, 2.0 after second) are identical

Test plan

• test_timeit_profile passes with the new mock
• No other tests in the file are affected (only import and one test method changed)
• The -3 line diff confirms this is a minimal, targeted refactor

Closes #806