refactor(harness): renaming prodotto tht (Onda -1)

Thoth (tht) è il prodotto, PSD è il cliente. Nessun riferimento al contesto
clinico nel codice.

Rinomine:
- comando+package nsp→tht (dir nsp/→tht/, 46 import, pyproject entry point)
- gate nsp-gate.js→tht-gate.js (+ rewrite token, relayIfNspFails→relayIfThtFails)
- workspace chirone.{example,test}.yaml→tht.{example,test}.yaml (generici)
- env THOTH_→THT_ (19 var) + NSP_ stragglers (NSP_HARNESS_ROOT, NSP_SESSION)
- commenti/docstring chirone/psdwp3/policlinico neutralizzati ('the reference
  implementation', 'the DWH')

Aggiunto [tool.setuptools.packages.find] include=['tht*'] (necessario: l'auto-
discovery rompeva con tht/ + workspaces/ come top-level multipli).

.env operatore aggiornato in-place (prefissi THT_, valori preservati, gitignored).

Verifica: pytest 109 passed, npm test 14 pass, tht phase meta --json OK, zero
residui nsp/THOTH_/NSP_/chirone nel package.

harness/tests/test_decisions_retract.py

@@ -1,4 +1,4 @@
-from nsp.decisions import append_decision, list_decisions
+from tht.decisions import append_decision, list_decisions
 
 
 def test_decision_retracted_in_audit_but_marked(tmp_path):
@@ -57,7 +57,7 @@ def test_empty_session_returns_empty_list(tmp_path):
 
 def test_decision_type_literal_includes_retracted():
     """decision_retracted e' un tipo valido (pydantic lo accetta)."""
-    from nsp.decisions import DecisionRecord
+    from tht.decisions import DecisionRecord
     from datetime import datetime, UTC
     d = DecisionRecord(
         seq=1, ts=datetime.now(UTC), type="decision_retracted",