v3 run 1 returned "no separating orbit" for six of fourteen boundaries,
including #13 and #15, the two the run existed to answer. Diagnosis was that
the gate compared ONE profile averaged over 40 s per side: a mean of band
percentages is a sound that never occurred, and 40 s of a livecoded track
averages toward the same grey for every orbit, so the orbits that actually
change look uninformative.

This replaces that with a distribution test:
  - reference windows are framed (3 s / 1.5 s hop) instead of averaged
  - each side is summarised by its MEDOID — an actual moment of the track —
    plus the median within-side distance, i.e. how varied that side is
  - an orbit votes only if it differs MORE across the switch than within
    either side (effect = sep - mean spread), not merely by a fixed distance
  - REF_MAX 40s -> 24s, so a reference stays one sound

NOT YET VALIDATED. Syntax-checked and smoke-run on boundary #11 only, which
still draws 3 voters and moves only its u0.15 estimate (3553.7 -> 3515.7);
whether #13/#15 recover needs the full 14-boundary run (~10 min) that has not
been done. Committed rather than parked so the reasoning is not lost — the
docstring's RESULT block still describes run 1 and must be rewritten with run
2's numbers before any boundary is taken from this.