fix(api): DecisionToken 狀態同步 (Y/n 持久化修復)

根本原因:
- resolve_incident_after_approval 只更新 Incident.decision.state
- 沒有更新獨立儲存的 DecisionToken (decision:{token} key)
- 導致下次 poll 時 get_or_create_decision 返回 READY 狀態的舊 token
- 前端繼續顯示 Y/n 按鈕

修復:
- 在 resolve_incident_after_approval 中同時更新 DecisionToken 狀態為 COMPLETED
- 確保整個決策鏈路狀態一致

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

apps/api/src/services/proposal_service.py

@@ -602,6 +602,39 @@ class ProposalService:
                 error=str(e),
             )
 
+        # 3. 更新 DecisionToken 狀態為 COMPLETED
+        # 關鍵修復: DecisionToken 獨立儲存在 decision:{token}
+        # 必須同步更新，否則下次 poll 會顯示 Y/n
+        decision_ok = False
+        try:
+            from src.services.decision_manager import get_decision_manager, DecisionState
+            decision_manager = get_decision_manager()
+            existing_token = await decision_manager._find_existing_token(incident_id)
+            if existing_token:
+                await decision_manager.update_token_state(
+                    existing_token.token,
+                    DecisionState.COMPLETED,
+                )
+                decision_ok = True
+                logger.info(
+                    "resolve_decision_token_updated",
+                    incident_id=incident_id,
+                    token=existing_token.token,
+                    new_state="completed",
+                )
+            else:
+                decision_ok = True  # 沒有 token 也算成功
+                logger.warning(
+                    "resolve_decision_token_not_found",
+                    incident_id=incident_id,
+                )
+        except Exception as e:
+            logger.exception(
+                "resolve_decision_token_error",
+                incident_id=incident_id,
+                error=str(e),
+            )
+
         # 只要 Redis 更新成功就算成功（API 只讀 Redis）
         success = redis_ok
         logger.info(
@@ -611,6 +644,7 @@ class ProposalService:
             success=success,
             redis_ok=redis_ok,
             db_ok=db_ok,
+            decision_ok=decision_ok,
         )
 
         return success