Wait out connection blips and recover as soon as the network returns

A socket drop now shows nothing for 1.5 s, then one calm status in the
Chat composer footer (Reconnecting… then Offline) instead of a notice row
that pushed the transcript. The wire reconnects at once on online, focus
and visibility, the Chat draft stays editable while offline, and the
locked document dims its ink.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>