Removed unused `import pytest` from line 5. The file uses no pytest
fixtures, marks, or raises, making this import dead code and causing
an F401 lint violation.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Implements lazy-cached load_signals() and pure match_signals() with
frequency/bandwidth/modulation/region scoring for the signal ID feature.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>