fix(synthesis): Use correct column name 'id' instead of 'execution_id'

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/reviewiq-pipeline/src/reviewiq_pipeline/stages/stage5_synthesize.py

@@ -433,10 +433,8 @@ Generate a complete synthesis with actionable insights.
         """Store synthesis in database."""
         await self.pool.execute("""
             UPDATE pipeline.executions
-            SET
-                synthesis = $2,
-                updated_at = NOW()
-            WHERE execution_id = $1::uuid
+            SET synthesis = $2
+            WHERE id = $1::uuid
         """, execution_id, json.dumps({
             "executive_narrative": synthesis.executive_narrative,
             "sentiment_insight": synthesis.sentiment_insight,