Add full shell, replaceable Omics adapter and bilingual interaction

Implement approved specification #32 and tickets #33-#37. Keep host authentication server-verified and pin session interaction language. Compile scoped base selectors for browser compatibility and retain full gutters during CSS pruning.

harness/tht/session/postgres_repository.py

@@ -306,6 +306,31 @@ class PostgresSessionRepository:
                 raise SessionError(f"Sessione non trovata: {manifest.id}")
         return self.get(manifest.id)
 
+    def ensure_interaction_language(
+        self, session_id: str, workspace_language: str
+    ) -> SessionSnapshot:
+        from tht.session.store import pin_interaction_language
+
+        self._require_uuid4(session_id)
+        with self._transaction() as connection:
+            self._lock_session(connection, session_id)
+            row = connection.execute(
+                text("SELECT manifest FROM thoth_sessions.sessions WHERE id = :id FOR UPDATE"),
+                {"id": session_id},
+            ).mappings().first()
+            if row is None:
+                raise SessionError(f"Sessione non trovata: {session_id}")
+            manifest = SessionManifest.model_validate(row["manifest"])
+            if pin_interaction_language(manifest, workspace_language):
+                connection.execute(
+                    text("UPDATE thoth_sessions.sessions "
+                         "SET manifest = CAST(:manifest AS jsonb), updated_at = pg_catalog.now() "
+                         "WHERE id = :id"),
+                    {"id": session_id,
+                     "manifest": json.dumps(manifest.model_dump(by_alias=True, mode="json"))},
+                )
+        return self.get(session_id)
+
     def read_artifact(self, session_id: str, key: str) -> str | None:
         self._require_uuid4(session_id)
         self._require_artifact_key(key)