v0.61.0 — Remove the knowledge-layer health score

Asked for by three consecutive field reports (2026-09-01, 09-02 §3.5, 09-04 §6), each saying the same
three things: it moved without a visible cause, nobody knew how to raise it, and it never blocked.

Reading what it computed explains all three. It was 100 − Σ penalties of the findings this invocation produced, with content catches excluded — so:

• an empty repo with no corpus at all scored 100%, the maximum;
• a repo with 44 memories and 16 sensors scored 0% as soon as one error finding with impact 100
  fired — an uncommitted file, a red CI. That is the reported "0% with a full corpus": not a bug, the
  formula;
• the observed "95% then 87%, unchanged corpus" was exactly 100 − 8 (briefing-missing) − 5 (bootstrap-incomplete), the first appearing and disappearing with the freshness of a local marker;
• a block sensor catching a real mistake — the knowledge layer doing its job — moved it by zero
  points, being classified as a content catch.

It measured how many complaints an invocation produced, and called that the health of the knowledge
layer. A number whose name designates something other than what it measures cannot be acted on.

Removed

• The knowledge-layer health: N% (target M%) line from every enforce stage.
• The enforcement-score-below-threshold finding (already hidden from the interactive gate in
  0.58.0 — which was the admission that it was not useful).
• enforcement.scoreThreshold from the config schema and both posture defaults.
• score from the enforce --json report, and baseline_health from the core gate verdict.
• computeBaselineHealth, buildBaselineHealthFinding and the BaselineHealth type from
  @hivelore/core.

Nothing else changes: what refused a change, and why, is reported exactly as before.