fix(ai): 修復 generate_incident_proposal tuple unpacking 錯誤

- _call_with_cache 返回 6 值 (含 ai_tokens/ai_cost)
- generate_incident_proposal 解包只取 4 值導致 ValueError
- 修復: 完整解包 6 值並傳遞 ai_tokens/ai_cost 到 proposal_dict

2026-03-29 ogt: Token/Cost 追蹤補遺

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

apps/api/src/services/openclaw.py

@@ -1261,7 +1261,8 @@ Focus on:
             "severity": severity,
         }
 
-        raw_response, provider, success, from_cache = await self._call_with_cache(
+        # 2026-03-29 ogt: 修復 tuple unpacking (Token/Cost 追蹤)
+        raw_response, provider, success, from_cache, ai_tokens, ai_cost = await self._call_with_cache(
             proposal_prompt,
             alert_context,
             signoz_metrics,
@@ -1290,6 +1291,7 @@ Focus on:
             )
 
             # 轉換為 proposal dict (optimization_suggestions 是 list[dict])
+            # 2026-03-29 ogt: 加入 ai_tokens/ai_cost 追蹤
             proposal_dict = {
                 "action": result.action_title,
                 "description": result.description,
@@ -1311,6 +1313,8 @@ Focus on:
                 "signoz_correlation": result.signoz_correlation,
                 "from_cache": from_cache,
                 "provider": provider,
+                "ai_tokens": ai_tokens,
+                "ai_cost": ai_cost,
             }
             return proposal_dict, provider, True