feat(feeds): add batch delete all feeds in folder functionality

[lcomplete]

Summary

• Add a Delete All Feeds in Folder button in the FeedsSetting UI, shown when a folder with feeds is selected, with a confirmation dialog before executing
• Fix the backend fillFolderConnectors to include persisted folders even when they have no connector items, and update the frontend navigation to correctly render empty folders
• Localize DeleteConfirmDialog cancel/delete button labels via i18n, and add new i18n keys for batch delete success, partial success, and failure messages in both en and zh-CN locales

Changes

• FeedsSetting.tsx: batch-delete logic using Promise.allSettled, snackbar feedback for all outcomes
• PrimaryNavigation.tsx: refactored folder-connector loop to show folders regardless of whether they have feeds
• ConnectorService.java: fillFolderConnectors now includes persisted folders with empty connector lists
• DeleteConfirmDialog.tsx: uses t('common:cancel') / t('common:delete') instead of hardcoded strings
• settings.json (en/zh-CN): added deleteFolderFeeds, deleteFolderFeedsConfirmDesc, folderFeedsDeleted, folderFeedsPartiallyDeleted, folderFeedsDeleteFailed keys

[augmentcode]

🤖 Augment PR Summary

Summary: Adds a “Delete All Feeds in Folder” action to the feeds settings UI and improves folder rendering when folders are empty.

Changes:

• Introduced batch feed deletion for a selected folder with confirmation and snackbar feedback for success/partial/failure outcomes.
• Updated mobile feeds navigation to render folders even when they have zero connector items.
• Adjusted backend folder-connector view generation to include persisted folders even when they have no connectors.
• Localized DeleteConfirmDialog cancel/delete button labels via i18n.
• Added new i18n strings (en + zh-CN) for the new delete-all-feeds-in-folder flow.

Technical Notes: Batch deletion uses Promise.allSettled to aggregate per-feed outcomes; backend now emits empty connector lists for persisted folders.

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[augmentcode]

Review completed. 1 suggestion posted.

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[augmentcode]

await Promise.all([refetchConnectors(), refetchFolders()]) can throw if either refetch fails, which would skip setDeletingFolderFeeds(false) and potentially leave the UI stuck in a deleting/disabled state. Consider handling refetch failures so the deleting flag is always cleared.

Severity: medium

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