feat(v0.6.0): review hardening — live active_skills clustering, computable fingerprints

Full codebase review (multi-agent, adversarially verified) surfaced several
documented-but-dead mechanisms and doc/code drift. Fixes:

- adam-observe: struggle signals now emit `active_skills`, so silent_drift's
  primary cluster key AND §5b skill-attribution sub-clustering (+1 rubric
  bonus) actually fire — both were silently dead (no struggle signal carried
  the field).
- adam-cooldown: new `--compute` CLI deterministically derives
  proposal_fingerprint. The exported computeProposalFingerprint() was never
  called and the analyst was told to hand-compute a djb2 hash it cannot
  reproduce. Spec now mandates a *stable* cluster id so fingerprints reproduce
  across /reflect runs. Removed one dead normalization line.
- spec: reinforcement proposals excluded from A/B tracking — agents/adam.md
  contradicted itself (:376 included, :476 excluded); SKILL.md aligned.
- adam-nudge: PENDING_CHECK_PATHS now mirrors the full install set
  (adam-utils / adam-batch / adam-rollback were missing).
- adam-explain: synthesized clustering summary carries `regressions: 0`
  (structural consistency with parsed summaries).
- docs: test-count drift (87/94 -> 126) and "350-line hook" (-> ~600) fixed;
  adam-score header documents severity_sum/severity_by_type; adam-batch §4
  reference corrected.

Tests: +12 assertions (114 -> 126), all green. New regression tests cover the
active_skills fix and --compute, plus boundary gaps the review flagged:
retry_loop/weak_agent thresholds, A/B exact +/-25% deltas, cooldown 30d
blacklist edge.

adam/scripts/adam-score.mjs

@@ -23,7 +23,8 @@
 // Output: JSON object
 //   {
 //     "sessions": [
-//       {"session_id": "...", "negative_count": N, "task_completed_count": M, "dampener": 1.0}
+//       {"session_id": "...", "negative_count": N, "task_completed_count": M,
+//        "severity_sum": S, "severity_by_type": {"<type>": N, ...}, "dampener": 1.0}
 //     ],
 //     "reinforcement_candidates": [
 //       {"skill_slug": "tdd-loop", "count": 3, "recent_ts": "..."}