fix(drift_repository): CAST(:param AS jsonb) 取代 :param::jsonb

asyncpg 不支援 named param 混用 :: cast 語法，導致 PostgresSyntaxError。
改用 CAST() 函數語法，與 SQLAlchemy text() named params 相容。

影響: drift_reports 現在可正常寫入 DB

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

apps/api/src/repositories/drift_repository.py

@@ -92,7 +92,7 @@ class DriftReportRepository:
                     VALUES
                         (:report_id, :namespace, :triggered_by, :scanned_at,
                          :high_count, :medium_count, :info_count,
-                         :items::jsonb, :interpretation::jsonb, :status, :created_at, :resolved_at)
+                         CAST(:items AS jsonb), CAST(:interpretation AS jsonb), :status, :created_at, :resolved_at)
                     ON CONFLICT (report_id) DO UPDATE SET
                         items = EXCLUDED.items,
                         interpretation = EXCLUDED.interpretation,
@@ -144,7 +144,7 @@ class DriftReportRepository:
             await db.execute(
                 text("""
                     UPDATE drift_reports
-                    SET interpretation = :interpretation::jsonb
+                    SET interpretation = CAST(:interpretation AS jsonb)
                     WHERE report_id = :report_id
                 """),
                 {