fix(llm): add fetch-models endpoint, fix SQL Lab INSERT (client_id truncation, sync mode, target_column, timestamp normalization)

- Add POST /api/llm/providers/fetch-models route with LLMClient.fetch_models()
- Add target_column to TranslationJob model/schema/service/orchestrator
- Fix SQL Lab execute: truncate client_id to 11 chars (varchar(11))
- Switch SQL Lab to sync mode (runAsync: false) — no Celery workers
- Fix polling: unwrap nested result from Superset query API
- Fix ClickHouse timestamp: normalize float timestamps to YYYY-MM-DD

backend/src/models/translate.py

@@ -42,7 +42,8 @@ class TranslationJob(Base):
     # Column mapping
     source_key_cols = Column(JSON, nullable=True, comment="Source key column names for composite key")
     target_key_cols = Column(JSON, nullable=True, comment="Target key column names for composite key")
-    translation_column = Column(String, nullable=True, comment="The column whose values will be translated")
+    translation_column = Column(String, nullable=True, comment="Source column whose values will be translated")
+    target_column = Column(String, nullable=True, comment="Target column for translated output (defaults to translation_column)")
     context_columns = Column(JSON, nullable=True, comment="Context column names included in LLM prompt")
 
     # LLM & processing settings
@@ -53,6 +54,7 @@ class TranslationJob(Base):
 
     # Environment association
     environment_id = Column(String, nullable=True, comment="Superset environment ID for datasource access")
+    target_database_id = Column(String, nullable=True, comment="Superset database ID for SQL Lab insert target")
 
     created_by = Column(String, nullable=True)
     created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
@@ -119,6 +121,7 @@ class TranslationRecord(Base):
     source_object_type = Column(String, nullable=True)  # query, dashboard, chart, dataset
     source_object_id = Column(String, nullable=True)
     source_object_name = Column(String, nullable=True)
+    source_data = Column(JSON, nullable=True, comment="Original source row key columns for upsert matching")
     status = Column(String, nullable=False, default="PENDING")  # PENDING, SUCCESS, FAILED, SKIPPED
     error_message = Column(Text, nullable=True)
     token_count_input = Column(Integer, nullable=True)
@@ -174,6 +177,7 @@ class TranslationPreviewRecord(Base):
     source_object_type = Column(String, nullable=True)
     source_object_id = Column(String, nullable=True)
     source_object_name = Column(String, nullable=True)
+    source_data = Column(JSON, nullable=True, comment="Original source row key columns for upsert matching")
     status = Column(String, nullable=False, default="PENDING")  # PENDING, APPROVED, REJECTED
     feedback = Column(Text, nullable=True)
     created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))