"""DSP Engine module.

Responsibility: extract objective measurable information from audio
signals.  No AI.  No semantic interpretation.  Produces measurable
observations only.

Future capabilities (per SPEC.md §23.3):
- Tempo, RMS, LUFS, Peak
- Spectral Centroid, Bandwidth, Contrast, Flux, Rolloff, Flatness
- MFCC, Chroma
- Harmonic Ratio, Stereo Width, Dynamic Range

Output: DSPFeatureCollection

This module must remain deterministic, produce reproducible values,
and must NOT infer semantics, classify mood, or generate recommendations.
"""