Surface CI status in channel details and the chat when relevant #29

Show CI status where people are already looking (the channel's details and the chat) when it matters to the work. This is not about new agent tools: agents already read, rerun and dispatch checks with gh through the shell.

Today

The details sidebar shows the lane's pull request with its checks, read again every 60 s while visible (apps/app/src/channel.tsx, apps/host/src/github.ts).

Surface when relevant

• In the chat: when the lane's PR checks finish or fail after the agent pushed, add a short line in the timeline, such as "CI failed: check (link)". The agent and participants then see it without asking. Don't repeat it for unchanged results.
• In details, on a failing check:
  • which job and step failed, with a link to its log;
  • a short excerpt of the failure, when it's cheap to get;
  • one action to ask the agent to fix it, which sends a normal message rather than running a tool.
• In details, on a running check: show that it's running and for how long, so nobody has to poll gh.
• Workflow runs the channel started that aren't tied to a PR: show them while they run and when they finish. For example, a bun desktop ci release run, alongside Show desktop release phases and notarization submissions while a build runs #167's release phases.

Out of scope

Dedicated CI tools for agents. Their gh use stays as it is.

Related: #12 (attention for finished or failed work). Tracked by #6. Migrated from TODO.md — Port from old Ace.