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/tht/mschema/models.py

@@ -0,0 +1,90 @@
+from datetime import datetime
+from pathlib import Path
+from typing import Self
+
+import yaml
+from pydantic import BaseModel, Field
+
+
+class _YamlModel(BaseModel):
+    def to_yaml(self, path: Path) -> None:
+        path.parent.mkdir(parents=True, exist_ok=True)
+        data = self.model_dump(by_alias=True, mode="json", exclude_defaults=False)
+        path.write_text(
+            yaml.safe_dump(data, sort_keys=False, allow_unicode=True, width=120)
+        )
+
+    @classmethod
+    def from_yaml(cls, path: Path) -> Self:
+        raw = yaml.safe_load(path.read_text())
+        return cls.model_validate(raw)
+
+
+class ColumnPhysical(BaseModel):
+    type: str
+    nullable: bool = True
+    pk: bool = False
+    default: str | None = None
+    comment: str = ""
+    examples: list[str] = []
+    is_enum: bool = False
+    eligible: bool = True
+    eligibility_reason: str = ""
+
+
+class ForeignKey(BaseModel):
+    columns: list[str]
+    ref_table: str
+    ref_columns: list[str]
+    name: str = ""
+
+
+class Index(BaseModel):
+    name: str
+    columns: list[str]
+    unique: bool = False
+    primary: bool = False
+    type: str = "btree"
+
+
+class TablePhysical(BaseModel):
+    comment: str = ""
+    row_count: int = 0  # stima da pg_class.reltuples
+    columns: dict[str, ColumnPhysical] = {}
+    foreign_keys: list[ForeignKey] = []
+    indexes: list[Index] = []
+
+
+class PhysicalSchema(_YamlModel):
+    database: str
+    db_schema: str = Field(alias="schema")
+    introspected_at: datetime
+    tables: dict[str, TablePhysical] = {}
+
+    model_config = {"populate_by_name": True}
+
+
+class ColumnAnnotation(BaseModel):
+    description: str = ""
+    synonyms: list[str] = []
+    concepts: list[str] = []
+    evidence: list[str] = []
+    notes: str = ""
+    eligible: bool | None = None
+
+
+class TableAnnotation(BaseModel):
+    description: str = ""
+    concepts: list[str] = []
+    notes: str = ""
+    columns: dict[str, ColumnAnnotation] = {}
+
+
+class Annotations(_YamlModel):
+    tables: dict[str, TableAnnotation] = {}
+
+    @classmethod
+    def from_yaml(cls, path: Path) -> "Annotations":
+        if not path.exists():
+            return cls()
+        return super().from_yaml(path)