Cron jobs configured with deliver labels from send_message(action='list')
like 'whatsapp:Alice (dm)' passed the label as a literal chat_id.
WhatsApp bridge failed with jidDecode error since 'Alice (dm)' isn't
a valid JID.
Now _resolve_delivery_target() strips display suffixes like ' (dm)' and
resolves human-friendly names via the channel directory before using
them. Raw IDs pass through unchanged when the directory has no match.
Fixes#1945.