fix: add source_language to glossary import + expose error details

- Set source_language from template data during import
- Return actual error message instead of generic one for debugging

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

routes/glossary_routes.py

@@ -591,6 +591,7 @@ async def import_glossary_template(
             glossary = Glossary(
                 user_id=user.id,
                 name=glossary_name,
+                source_language=template_data.get("source_lang", "fr"),
                 created_at=datetime.now(timezone.utc),
                 updated_at=datetime.now(timezone.utc),
             )
@@ -625,11 +626,11 @@ async def import_glossary_template(
                 },
             )
     except Exception as e:
-        logger.error(f"Failed to import glossary template {template_id}: {e}")
+        logger.error(f"Failed to import glossary template {template_id}: {e}", exc_info=True)
         return JSONResponse(
             status_code=500,
             content={
                 "error": "IMPORT_ERROR",
-                "message": "An error occurred while importing the template.",
+                "message": f"Import failed: {str(e)}",
             },
         )