feat(api): return 400 for database schema errors in V3 search

- Updated api_crud_v3 and api_crud_v3_nested to detect 'database_schema'
  errors (like Unknown Column) and return a 400 Bad Request instead of
  a generic 500 Internal Server Error.
- Added missing error handling for sql_select failure in get_child_obj_li.

app/routers/api_crud_v3.py

@@ -366,7 +366,11 @@ async def search_obj_li(
     if sql_result is False:
         # Standardized rich error bubbling
         db_err = format_db_error(get_last_sql_error())
-        return mk_resp(data=False, status_code=500, response=response, status_message="Search failed due to database error.", details=db_err.dict())
+        
+        # If it's a schema error (like Unknown Column), it's a 400 Bad Request
+        status_code = 400 if db_err.category == "database_schema" else 500
+        
+        return mk_resp(data=False, status_code=status_code, response=response, status_message="Search failed due to database error.", details=db_err.dict())
 
     if sql_result:
         resp_data_li = [base_name(**record).dict(by_alias=serialization.by_alias, exclude_unset=serialization.exclude_unset, exclude_defaults=serialization.exclude_defaults, exclude_none=serialization.exclude_none) for record in sql_result]

app/routers/api_crud_v3_nested.py

@@ -118,6 +118,15 @@ async def get_child_obj_li(
         as_list=True,
     )
 
+    if sql_result is False:
+        # Standardized rich error bubbling
+        db_err = format_db_error(get_last_sql_error())
+        
+        # If it's a schema error (like Unknown Column), it's a 400 Bad Request
+        status_code = 400 if db_err.category == "database_schema" else 500
+        
+        return mk_resp(data=False, status_code=status_code, response=response, status_message="Search failed due to database error.", details=db_err.dict())
+
     if sql_result:
         resp_data_li = [base_name(**record).dict(by_alias=serialization.by_alias, exclude_unset=serialization.exclude_unset, exclude_defaults=serialization.exclude_defaults, exclude_none=serialization.exclude_none) for record in sql_result]
         return mk_resp(data=resp_data_li, response=response)