维护者确认 #3062 fix(file-browser): reject/emit error on rg fatal exit

## 维护者确认

PR [#3062](https://github.com/makecindy/cindy/pull/3062) 触发了 arch 类维护者确认门。

**触发原因**: core-paths(核心路径改动 ≥ 150 行)

**确认方式**: 直接在 PR 上 Approve 即放行;需要修改请 Request Changes,作者改完后重新 Approve。

---
关联 PR:#3062(作者 @Battleplus);本 issue 由 review-pr 流程自动创建,用于先讨论该 PR 涉及的技术架构调整,维护者确认后 PR 会恢复推进。

This is a maintainer-confirmation issue for PR #3062, not an independent implementation task. Review the linked PR's core-path changes and its architecture implications first; the work is done when a maintainer approves the PR, or requests changes that the author then addresses and gets approved.

Written by the indexing model from the issue text.