Fix cashflow: use DB column name 'description' not ORM attribute name

The Transaction model maps description_enc -> 'description' column.
Raw SQL must use the actual DB column name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/v1/predictions.py

@@ -214,7 +214,7 @@ async def cashflow_forecast(
 
     # Fetch recurring transactions (expenses)
     rec_result = await db.execute(text("""
-        SELECT description_enc, amount::float, recurring_rule, date
+        SELECT description, amount::float, recurring_rule, date
         FROM transactions
         WHERE user_id = CAST(:uid AS uuid)
           AND is_recurring = TRUE