feat(translate): enhanced target table column mapping + fix multi-language save

Multi-language save fix:
- MultiSelect.svelte: selected prop changed to $bindable([])
  (without $bindable, bind:selected never propagated to parent component,
  so target_languages always stayed as default ['en'])

Target table column mapping (INSERT enhancement):
- target_language_column — stores language code (e.g. 'ru', 'en')
- target_source_column — stores original source text
- target_source_language_column — stores detected BCP-47 source language
- SQL generator includes these columns in INSERT when configured
- Frontend: 4 input fields under 'Target Column Mapping' section
  with clear labels, placeholders, and i18n hints

Backend: model, schema, service, orchestrator
Frontend: job config page, i18n en+ru
DB: 3 new columns added to production

backend/src/models/translate.py

@@ -42,6 +42,9 @@ class TranslationJob(Base):
     target_key_cols = Column(JSON, nullable=True, comment="Target key column names for composite key")
     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)")
+    target_language_column = Column(String, nullable=True, comment="Target column for language code (e.g. 'ru', 'en')")
+    target_source_column = Column(String, nullable=True, comment="Target column for source/original text")
+    target_source_language_column = Column(String, nullable=True, comment="Target column for detected source language (BCP-47)")
     context_columns = Column(JSON, nullable=True, comment="Context column names included in LLM prompt")
 
     # LLM & processing settings

backend/src/plugins/translate/orchestrator.py

@@ -23,7 +23,7 @@ from collections.abc import Callable
 from datetime import UTC, datetime
 from typing import Any
 
-from sqlalchemy.orm import Session, selectinload
+from sqlalchemy.orm import Session, joinedload, selectinload
 
 from ...core.config_manager import ConfigManager
 from ...core.logger import belief_scope, logger
@@ -338,9 +338,10 @@ class TranslationOrchestrator:
         run: TranslationRun,
     ) -> dict[str, Any]:
         with belief_scope("TranslationOrchestrator._generate_and_insert_sql"):
-            # Fetch successful records
+            # Fetch successful records with eager-loaded language data
             records = (
                 self.db.query(TranslationRecord)
+                .options(joinedload(TranslationRecord.languages))
                 .filter(
                     TranslationRecord.run_id == run.id,
                     TranslationRecord.status == "SUCCESS",
@@ -378,6 +379,17 @@ class TranslationOrchestrator:
                     if k not in columns:
                         columns.append(k)
 
+            # Add target metadata columns for enhanced table mapping
+            if job.target_source_column and job.target_source_column not in columns:
+                columns.append(job.target_source_column)
+            if job.target_language_column and job.target_language_column not in columns:
+                columns.append(job.target_language_column)
+            if job.target_source_language_column and job.target_source_language_column not in columns:
+                columns.append(job.target_source_language_column)
+
+            # Resolve the primary target language for INSERT
+            primary_language = (job.target_languages or ["en"])[0]
+
             rows_for_sql = []
             for rec in records:
                 row_data = {}
@@ -401,6 +413,21 @@ class TranslationOrchestrator:
                 if effective_target:
                     row_data[effective_target] = rec.target_sql or ""
 
+                # Source text column: INSERT original source text
+                if job.target_source_column:
+                    row_data[job.target_source_column] = rec.source_sql or ""
+
+                # Language column: INSERT language code (e.g. 'ru', 'en')
+                if job.target_language_column:
+                    row_data[job.target_language_column] = primary_language
+
+                # Source language column: INSERT detected source language (BCP-47)
+                if job.target_source_language_column:
+                    detected = "und"
+                    if rec.languages and len(rec.languages) > 0:
+                        detected = rec.languages[0].source_language_detected or "und"
+                    row_data[job.target_source_language_column] = detected
+
                 # Key columns from source data
                 if job.target_key_cols:
                     for k in job.target_key_cols:

backend/src/plugins/translate/service.py

@@ -255,6 +255,9 @@ class TranslateJobService:
             target_key_cols=payload.target_key_cols or [],
             translation_column=payload.translation_column,
             target_column=payload.target_column,
+            target_language_column=payload.target_language_column,
+            target_source_column=payload.target_source_column,
+            target_source_language_column=payload.target_source_language_column,
             context_columns=payload.context_columns or [],
             target_languages=target_languages,
             provider_id=payload.provider_id,
@@ -392,6 +395,9 @@ class TranslateJobService:
             target_key_cols=source.target_key_cols,
             translation_column=source.translation_column,
             target_column=source.target_column,
+            target_language_column=source.target_language_column,
+            target_source_column=source.target_source_column,
+            target_source_language_column=source.target_source_language_column,
             context_columns=source.context_columns,
             target_languages=source.target_languages,
             provider_id=source.provider_id,
@@ -494,6 +500,9 @@ def job_to_response(job: TranslationJob, dict_ids: list[str] | None = None) -> T
         target_key_cols=job.target_key_cols or [],
         translation_column=job.translation_column,
         target_column=job.target_column,
+        target_language_column=job.target_language_column,
+        target_source_column=job.target_source_column,
+        target_source_language_column=job.target_source_language_column,
         context_columns=job.context_columns or [],
         target_languages=job.target_languages,
         provider_id=job.provider_id,

backend/src/schemas/translate.py

@@ -42,6 +42,9 @@ class TranslateJobCreate(BaseModel):
     target_key_cols: list[str] | None = Field(default_factory=list, description="Target key column names")
     translation_column: str | None = Field(None, description="Source column to translate")
     target_column: str | None = Field(None, description="Target column for translated output (defaults to translation_column)")
+    target_language_column: str | None = Field(None, description="Target column for language code (e.g. 'ru', 'en')")
+    target_source_column: str | None = Field(None, description="Target column for source/original text")
+    target_source_language_column: str | None = Field(None, description="Target column for detected source language (BCP-47)")
     context_columns: list[str] | None = Field(default_factory=list, description="Context column names")
     target_language: str | None = Field(None, description="Target language code [DEPRECATED: use target_languages]")
     target_languages: list[str] | None = Field(default_factory=list, description="List of BCP-47 target language codes")
@@ -72,6 +75,9 @@ class TranslateJobUpdate(BaseModel):
     target_key_cols: list[str] | None = None
     translation_column: str | None = None
     target_column: str | None = None
+    target_language_column: str | None = None
+    target_source_column: str | None = None
+    target_source_language_column: str | None = None
     context_columns: list[str] | None = None
     target_language: str | None = None
     target_languages: list[str] | None = None
@@ -104,6 +110,9 @@ class TranslateJobResponse(BaseModel):
     target_key_cols: list[str] | None = None
     translation_column: str | None = None
     target_column: str | None = None
+    target_language_column: str | None = None
+    target_source_column: str | None = None
+    target_source_language_column: str | None = None
     context_columns: list[str] | None = None
     # source_language removed — deprecated, per-row auto-detected
     target_languages: list[str] | None = None