fix(HEL-412): 刷新降级不再整次失败，并补齐准备中提示

手动刷新与自动补跑共用可用数据判定：日线推算或上一交易日快照记为部分/准备中成功，避免前端误报刷新失败。HTTP JSON 解析错误不再把请求正文写入日志。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

ARCHITECTURE.md

@@ -54,7 +54,9 @@ background scheduler
   feature repository mixins; do not add feature queries to it.
 - `backend/jobs/` owns job definitions, locks, retries, idempotency, and persisted run state.
   `backend/jobs/service.py` is the application-facing owner of scheduler start/stop, manual
-  refresh submission, and periodic refresh coordination.
+  refresh submission, and periodic refresh coordination. `backend/jobs/refresh.py` owns
+  whether a dashboard payload is a usable refresh result versus a failed job, and whether
+  after-hours official catch-up is due.
 - `backend/llm/` owns model selection, membership/quota checks, fallback, provider transport,
   streaming rules, and call audit. Feature agents only prepare messages and interpret
   feature-specific results.