feat(unwrapped): explorable feature-space map of the sample corpus (#81)

ParVagues Unwrapped — a Ship's Bridge dark explorable over unwrapped.json:
- The map: canvas scatter of all 1,485 samples; pick any 2 of the 5 named
  superfeature axes (or raw features); colour by family / audio-cluster /
  folder-kind / folder-agreement; hover to identify, CLICK TO AUDITION the .wav.
- The five axes: PCA loading bars (what composes each superfeature) + RF
  family-discriminator importances (centroid + temporal-centroid on top).
- Family fingerprints: per-family beeswarm on a switchable feature — the
  kick-punchy / bass-sustained split made visible.
- Folders are loose: family x audio-cluster contingency grid (ARI 0.25) — the
  timbre-not-label story, the data behind 'a folder is a loose grouping'.
Zero npm deps; fleet family colours; magenta reserved for the audition pulse.