Support torrent IP blocklist URLs

[thsnkhn]

Problem

Torrent users cannot configure an IP blocklist or synchronize a blocklist from a URL.

Goal

Allow Harbor to download, validate, cache, and apply an IP blocklist to torrent peer connections.

Acceptance criteria

• Settings accepts a blocklist URL and provides an enable or disable control.
• Harbor validates the response before replacing the active cached list.
• A failed refresh keeps the last valid cached list.
• Users can refresh the list manually and see its last successful update time.
• The blocklist applies to new torrent peer connections.
• Harbor reports whether the current aria2 backend can enforce the selected blocklist format.
• If aria2 cannot enforce IP blocklists, document the required backend change before adding a misleading UI.
• Disabling the feature restores normal peer behavior.

Source

Two users requested IP blacklist or blocklist URL support in the Harbor 1.7.0 Reddit announcement.