fix: 自动备份400错误修复及配置切换调度缺陷

[lostiv]

• throwTranslatedError 优先使用 data.error 中的具体错误信息，避免校验失败原因被丢弃
• checkAndBackup 增加活跃配置变更检测，切换 WebDAV 配置后立即触发新备份
• 补充 VALIDATION_FAILED 及备份相关错误码映射

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between dd3c415 and 5366501.

📒 Files selected for processing (1)

• src/services/backendAdapter.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• src/services/backendAdapter.ts

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📝 Walkthrough

Summary by CodeRabbit

更新说明

• Bug Fixes

  • 改进备份功能，在 WebDAV 配置更改时自动重置备份计时，确保下次备份立即执行
  • 优化后端错误处理机制，支持服务器返回的详细错误信息显示

• New Features

  • 新增五个备份相关操作的多语言错误提示信息

Walkthrough

检测并在 WebDAV 活动配置切换时重置备份计时器；增强后端错误解析以优先使用服务器返回的 error 字段，并新增五个备份相关本地化错误码。

Changes

备份功能和错误处理增强

Layer / File(s)	Summary
备份配置变化检测 server/src/services/backupService.ts	在 checkAndBackup() 中检测 activeConfigId 变化，当 WebDAV 配置切换时重置 lastBackupTime 并更新 lastActiveConfigId，使新配置的备份可立即执行。
后端错误解析与本地化消息 src/services/backendAdapter.ts, src/utils/backendErrors.ts	throwTranslatedError 现在尝试读取响应 JSON 的 error 字段并在存在时直接抛出该消息；ERROR_MESSAGES 新增五个备份相关错误码（VALIDATION_FAILED、UPDATE_BACKUP_SETTINGS_FAILED、FETCH_BACKUP_SETTINGS_FAILED、FETCH_BACKUP_STATUS_FAILED、TRIGGER_BACKUP_FAILED）的中英文翻译。

预估审查工作量

🎯 3 (Moderate) | ⏱️ ~20 分钟

建议标签

bug, frontend, backend

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	PR 标题遵循 Conventional Commits 格式：type(scope): description，使用了 fix 类型，清晰描述了备份错误修复和配置切换问题。
Description check	✅ Passed	PR 描述详细说明了三个主要改动，与代码变更相符：错误信息处理优化、配置切换检测和错误码映射。
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 1

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Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/services/backendAdapter.ts`:
- Around line 81-89: The current handler reads res.json() into data and directly
assigns data.error to serverError then throws it, which can stringify objects to
“[object Object]”; update the logic in the backendAdapter response handling
(around res.json(), code, serverError) to type-guard data.error: if typeof
data.error === 'string' && data.error.trim() !== '' then throw new
Error(data.error), otherwise do not throw the raw value and instead fall back to
the existing code-based translation/fallback path (use the code variable to
produce a user-friendly message); ensure you do not expose non-string error
objects directly to the UI.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 43d0ae1 and dd3c415.

📒 Files selected for processing (3)

• server/src/services/backupService.ts
• src/services/backendAdapter.ts
• src/utils/backendErrors.ts

📜 Review details

🧰 Additional context used

📓 Path-based instructions (2)

src/services/**

⚙️ CodeRabbit configuration file

src/services/**: API 服务层。审查时请关注： 1. fetch 请求的超时处理（AbortController） 2. 错误处理和用户友好的错误信息翻译 3. API 密钥/Token 的传输安全性 4. 请求重试和降级策略 5. WebDAV/后端代理的 CORS 处理

Files:

• src/services/backendAdapter.ts

server/src/services/**

⚙️ CodeRabbit configuration file

server/src/services/**: 后端服务层。审查时请关注： 1. 加密解密逻辑的正确性（AES-256-GCM） 2. 密钥管理和随机性 3. 错误处理不泄露敏感信息

Files:

• server/src/services/backupService.ts

🔇 Additional comments (2)

server/src/services/backupService.ts (1)

356-360: 配置切换后立即触发备份的策略实现正确。

这段逻辑能确保活跃配置变更后不受旧间隔限制，符合自动备份预期。

src/utils/backendErrors.ts (1)

54-58: 错误码映射补充完整且一致。

新增文案覆盖了校验失败与备份链路常见错误，能提升前端提示质量。