fix(usage): 流式终端 usage 以更完整值为准，Codex CLI 显式选择 response 解析器

- 新增 StandardizedUsage::signal_score/is_more_complete_than/choose_more_complete，流式合并与终端落库均按信号完整度择优
- OpenAI Chat/CLI 解析器支持仅 usage 的终结 chunk 与 response.completed usage
- Codex provider 注入 provider_stream_event_api_format=openai:cli，解析器选择改由 report_context 显式决定
- usage_mapper 扩展嵌套 response/message/item 兼容 Claude message_start/message_delta 及 Gemini stream chunks
- usage SQL upsert 在终态（completed/failed/cancelled）时按 GREATEST 写入 token/费用镜像列

apps/aether-gateway/src/tests/ai_execute/stream_cli/direct.rs

@@ -543,6 +543,8 @@ async fn gateway_executes_codex_cli_stream_via_local_decision_gate_after_oauth_r
         tokio::time::sleep(std::time::Duration::from_millis(10)).await;
     }
     let stored_usage = stored_usage.expect("usage should be recorded");
+    assert_eq!(stored_usage.input_tokens, 1);
+    assert_eq!(stored_usage.output_tokens, 2);
     assert_eq!(stored_usage.total_tokens, 3);
     assert!(stored_usage.request_body.is_none());
     assert!(stored_usage.provider_request_body.is_none());