fix: persist environment selection, support Kilo AI provider, resolve Superset virtual columns for translation preview

- Add environment_id to TranslationJob model/schema/API + DB migration
- Pass environmentId from page to TranslationPreview and fetchPreview
- Fix _fetch_sample_rows: use result_type='samples' to include virtual cols
- Add 'kilo' and 'openrouter' to supported LLM provider types
- Make response_format conditional (skip for non-OpenAI upstream providers)
- Remove source_table field from form (redundant with datasource)
- Restore datasourceSearch display from saved job on page load
- Add request/response logging for LLM API calls

backend/src/core/database.py

@@ -475,6 +475,38 @@ def _ensure_filter_source_enum_values(bind_engine):
 # @SIDE_EFFECT: Executes ALTER TABLE statements against dataset review tables in the application database.
 # @RELATION: [DEPENDS_ON] ->[DatasetReviewSession]
 # @RELATION: [DEPENDS_ON] ->[ImportedFilter]
+def _ensure_translation_jobs_columns(bind_engine):
+    with belief_scope("_ensure_translation_jobs_columns"):
+        table_name = "translation_jobs"
+        inspector = inspect(bind_engine)
+        if table_name not in inspector.get_table_names():
+            return
+
+        existing_columns = {
+            str(column.get("name") or "").strip()
+            for column in inspector.get_columns(table_name)
+        }
+
+        if "environment_id" not in existing_columns:
+            try:
+                with bind_engine.begin() as connection:
+                    connection.execute(
+                        text(
+                            "ALTER TABLE translation_jobs "
+                            "ADD COLUMN environment_id VARCHAR"
+                        )
+                    )
+                logger.reflect(
+                    "Added environment_id column to translation_jobs",
+                )
+            except Exception as migration_error:
+                logger.explore(
+                    "Failed to add environment_id to translation_jobs",
+                    extra={"error": str(migration_error)},
+                )
+                raise
+
+
 def _ensure_dataset_review_session_columns(bind_engine):
     with belief_scope("_ensure_dataset_review_session_columns"):
         inspector = inspect(bind_engine)
@@ -573,6 +605,7 @@ def init_db():
         ensure_connection_configs_table(engine)
         _ensure_filter_source_enum_values(engine)
         _ensure_dataset_review_session_columns(engine)
+        _ensure_translation_jobs_columns(engine)
 
 
 # [/DEF:init_db:Function]