Nothing covers a rejected room-invite read: the group strip must still draw the Invite button and mint nothing by itself #1047

Owner: Dev4

What is missing

plugins/social/client.js GroupStrip (main 1d5b5a5f) handles a rejected room-invite read like this:

host('room-invite', { roomId }).then((value) => {
  if (gone) return
  setShown({ roomId, invite: liveInviteOf(value) })
  setRead({ roomId, done: true })
}, () => { if (!gone) setRead({ roomId, done: true }) })

The reject handler marks the read done so the button is drawn and nothing is minted — that is the behaviour the strip needs on an older host that has no room-invite endpoint. Nothing tests it: no case covers the reject branch, so a regression that leaves read.done false on error makes the strip render no invite control at all (the button only appears when known is true) and no test would go red.

This is Reviewer's non-blocking on #1040.

Expected

A host that rejects room-invite still gets a working Invite by link: the button is drawn once the read settles, clicking it mints, and the failure is not shown as a note.

Scope

• plugins/social/test/social.test.js — extend the #1038 case (or add one beside it) with a host whose room-invite read rejects.
• No source change expected; if the case shows the button really is missing on reject, that is a bug fix in the same pull request, not a separate issue.
• Test-only: no changelog.d/ fragment, Docs-not-needed: in the commit message if arch-docs fires.

Acceptance

1. With room-invite rejecting: [data-flybot=group-strip-invite] exists after the read settles, and no room-invite-mint call happens by itself.
2. Clicking it calls room-invite-mint exactly once and shows the minted URL.
3. No error note is rendered for the read failure (the strip just acts as if the room had no link).
4. Knife: leave read.done false in the reject handler → case 1 goes red (no button), the rest stay green.
   enhancement, area:ui, area:social, agent-ready.