Fix tracked ring-mod wet path and YIN interpolation

[user1303836]

Summary

• stop scaling pitch-track wet level by detector confidence and only stay dry until a tracked pitch is available
• fix the sign of the YIN parabolic interpolation offset
• add a tighter 110 Hz detector accuracy test and update the README to match the new tracking behavior

Testing

• cmake -B build -DCMAKE_BUILD_TYPE=Release -DHDN_BUILD_TESTS=ON
• cmake --build build --config Release
• ctest --test-dir build --build-config Release --output-on-failure