[iamnbutler]

After you remove your copy of a GitHub project that a teammate also has, the project is still known through their channels. All Projects then kept an empty group of yours for it, with a +, above <project> · <teammate>, and the group stayed after a reload.

All Projects now leaves out your group for a project when you have no channels in it and no checkout of it open on this host. The teammates' groups for it stay. A project you have open still shows your group with its +, even with no channels. To start a channel in a teammate's GitHub project that you haven't opened, select it in the project picker.

Fixes #637. Map: ^346.

Smoke: loopback source host with its own ACE_HOME, headless Chromium, and two checkouts whose origin is octocat/Spoon-Knife. A channel rivera-spoon was made in the second checkout as rivera. Playwright rewrote the host's frames so the channel was listed from rivera-mac and its checkout was not one of this host's projects, as it would be from a teammate's Mac.

• main, with the project removed: All Projects showed "Spoon-Knife" (Collapse + "New channel in Spoon-Knife") and an empty group above "Spoon-Knife · rivera / rivera-spoon".
• This branch, with the project removed: only "Spoon-Knife · rivera / rivera-spoon".
• This branch, with the project open: "Spoon-Knife" with its New channel button, then "Spoon-Knife · rivera".

Built in Ace

No: made from Claude Code (a fix-train worker), with headless Chromium for the smoke test. Dogfooding gap tracked in #5.