e2e flake: shell-ui's first-run page never comes back after its reload (#sidebar-agent missing) #792

Seen on #752's CI (run 41154118657, e2e shard 2/4, shell-ui). #753, stacked on it with all of #752's code plus media's, passed the same shard. #745 below it passed too.

What failed: after the first run's hello (crates/e2e/src/lanes/shell.rs:1144), the lane reloads the page and waits 30 s for #layout shown, one #chats .chat-row and a #frames iframe (shell.rs:1145). That never held, so everything after it failed in turn:

• "reloaded once it is made, the chat shows no card" (chats_now was 1: nothing was made twice);
• "its chat is framed … answers the first message at once" (typed: false: the composer never took text);
• the desktop-width sidebar checks;
• finally shell-ui stopped early: nothing on the page matches #sidebar-agent (shell.rs:4937, 120 s).

So the platform's state was right (one chat), but the reloaded shell never drew it.

Not yet known: whether the reload hit a node mid-boot or a deploy going out (#483's case), or the shell's start stalled (its "Still loading… Reload" line wasn't checked here). The e2e-scratch-2 artifact of that run keeps the node logs.

Related: #483, #782, #743/#748 (the front door).