Add safe local cleanup controls for chat history and downloaded QDN content

[QuickMythril]

Local ID: F-HELP-19

Source: Qortium Help feedback mr9dri from Saybin on 2026-07-06.

Problem

Users have asked for visible controls to clear local chat history and downloaded QDN content, especially near the existing settings that govern chat retention and maximum storage capacity.

Suggested scope

• Decide whether these controls belong in Home, the Node app surface, Core settings, or a combination.
• Add a clear delete-chat-history action near the chat retention setting, if the data boundary is well-defined.
• Add a clear delete-downloaded-content action near the maximum storage setting, if the storage boundary is well-defined.
• Require confirmation for destructive actions and make the local-only effect explicit.
• Preserve wallet, account, and QDN publish data that should not be removed by these cleanup actions.
• Report success/failure and any remaining storage that could not be cleared.

Notes

This needs design and ownership confirmation before implementation because the requested actions are destructive and touch local storage/account boundaries.