navigator.clipboard only works in a secure context, so copy silently failed when served over a LAN IP on http. Add a robustCopy() with a textarea+execCommand fallback (used by group-link, address and channel-link copy). The group/channel 'Link' button now toggles a visible, selectable URL row beneath the group with a working copy button. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>