[iamnbutler]

Fix train leftovers from the Ace map.

• ^897 ace open now prints Opened <origin> in your browser, signed in to this host. (no token). The signed-out banner names this build's command: the host's 401 on /ws carries config.command, which Ace Helper now derives from its identifier (ace, ace-canary, ace-dev), matching the link the app installs.
• ^882 ace directory <url> against a running host prints Joined <url> before the sync status.
• ^106 The sidebar's Team directory card on a Mac that still serves a directory it has left says so and offers Join (re-serves and rejoins) instead of Create directory.
• ^559 A deleted message (anything with no available action) gets no hover toolbar, instead of disabled React, Copy and Link.

Refs #636, #619, #609, #625.

Smoke on an isolated bun ace serve (own home, config, keychain, port 5130): ace open printed the line; a signed-out page read Run ace open, and a host with config.command = "ace-canary" read Run ace-canary open; ace directory <served url> printed Joined …; after ace directory off the card read "This Mac serves your team's directory but isn't in it…", and Join rejoined it; after deleting a message, hovering Message deleted showed no toolbar while the other message kept Add reaction, Copy, Copy message link, More.

Built in Ace

No. Built by a Claude Code fix-train worker from a terminal, with a headless Chromium (Playwright) for the browser smoke, since the train runs many parallel unattended workers outside Ace. Gap tracked under #5.