fix(sensing-server): fix CSI per-node count clamp — #803 (part 2)

The pure-CSI per-node path clamped its own occupancy estimate before the
aggregator could read it. estimate_persons_from_correlation (DynamicMinCut)
returns 0-3, but it was mapped to a score via `corr_persons / 3.0`, putting
2 people at 0.667 — just under the 0.70 up-threshold of
score_to_person_count — so the per-node count never climbed past 1, leaving
node_max stuck at 1 for CSI-only nodes even when the min-cut cleanly
separated two people.

Replace the lossy /3.0 mapping with a threshold-aligned corr_persons_to_score
(1->0.40, 2->0.74, 3->0.96) whose steady state round-trips back to the same
count through the EMA + hysteresis bands, while still gating transient noise.

A convergence test replays the exact CSI-loop EMA and asserts min-cut=2 now
reports 2 / 3 reports 3 / 1 reports 1, plus a regression test documenting
that the old /3.0 mapping pinned two people to 1.

Full suite: 586 passed, 0 failed.

Co-Authored-By: claude-flow <ruv@ruv.net>