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_vector_dual_key.py

@@ -5,9 +5,9 @@ API keys against the same pgvector REST endpoint, with distinct roles
 (vector_reader / vector_writer). This test pins the dual-key construction and
 the workstation write-guard.
 """
-from nsp.cli._guards import has_vector_write_rest, require_vector_write_allowed
-from nsp.config import Config, DatabaseConfig, RestConfig
-from nsp.vectorstore.rest_client import VectorRestClient
+from tht.cli._guards import has_vector_write_rest, require_vector_write_allowed
+from tht.config import Config, DatabaseConfig, RestConfig
+from tht.vectorstore.rest_client import VectorRestClient
 
 
 def _minimal_config(**kw) -> Config: