herdr web ui v0.3.1

Changed

• Remote PCs use the remote-v2 runtime, which carries 0.3.0's server changes (chat pages, the
  Codex conversation fixes, server-side message sending and 304 answers) to the remote side.
  A PC connected with the remote-v1 bridge needs Update bridge… once; its herdr sessions are
  kept.
• A PC that only an update or an approval can reconnect says so: it stops retrying, shows the next
  step under its name with the button that does it (Update bridge… or Set up…), and a line
  under the header says the same, so it shows on a phone with the drawer closed.