* fix: 改进 KnowledgeBaseManager 和 KBHelper 中的初始化错误处理
* fix: 改进知识库初始化和重排序错误处理，增强日志记录
* fix: 改进知识库模块初始化和检索错误处理
* fix(ui): handle kb init errors in list cards
display a dedicated error state for knowledge base cards that fail
initialization, including a visible badge and error details
prevent navigation and edit actions for failed cards while keeping
delete available, and hide normal stats/description for error items
add list.initError locale strings for en-US, ru-RU, and zh-CN
* fix(kb): avoid replacing helper on init failure
Initialize a new KB helper before swapping instances so a failed re-init
does not break the active knowledge base service.
If initialization fails, restore in-memory KB settings and keep the
existing helper and previous init error state.
Also clear stale init_error after successful vector DB initialization to
prevent outdated error reporting.
* test(kb): add kb manager resilience tests
cover initialization failure and recovery scenarios to guard
against regressions in kb error handling
include reference assets under refs for test validation
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Co-authored-by: RC-CHN <1051989940@qq.com>
