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/filesystem_repository.py

@@ -106,6 +106,19 @@ class FilesystemSessionRepository:
         path = self._artifact_path(session_dir, key)
         return path.read_text() if path.exists() else None
 
+    def ensure_interaction_language(
+        self, session_id: str, workspace_language: str
+    ) -> SessionSnapshot:
+        from tht.session.store import pin_interaction_language
+
+        session_dir = self._session_dir(session_id)
+        with self._lock(session_dir):
+            self._require_existing(session_dir, session_id)
+            manifest = SessionManifest.from_yaml(session_dir / MANIFEST)
+            if pin_interaction_language(manifest, workspace_language):
+                self._write_manifest(session_dir, manifest)
+        return self.get(session_id)
+
     def write_artifact(self, session_id: str, key: str, content: str) -> None:
         session_dir = self._session_dir(session_id)
         with self._lock(session_dir):