* fix(core): signal beats read the same at any decode rate and refuse a grid in the tracker
The tracker resamples every channel to 22.05 kHz and averages their band power, so the
CLI's native-rate decode and Studio's AudioContext decode get the same beats, and a mono
file and the same sound on two channels get identical ones.
The no-steady-beat floor moves from analyzeMusicFromSignal into the tracker, so
hyperframes audio, grep_audio and beats share one floor. It is 0.15: above every one of
66 synthetic ambient, speech, scattered-effect and noise clips (max 0.122), where the
wrapper's 0.2 also refused a third of GTZAN's produced music.
* feat(core): signal downbeats follow chord changes, and sections hear harmony
The tracker now keeps a 10 fps chroma beside its band energies. Downbeats weigh where the
chords change, over one beat and over two, with the low-end hit, instead of the low end
alone. Sections compare timbre and harmony equally.
Tuned on GTZAN's dev half: the tempo prior narrows to 0.8 octave, the local tempo stays
within 10% of the global one, and beats sit 15 ms after the onset peak, where annotators
put them.
* chore(core): trim redundant audio analysis comments
* refactor(core): keep the rhythm files under their comment share
Drops doc comments whose function or field name already says the same thing.
Xuanru Li
695110e46b