feat(honcho): add workspace picker and peer name confirmation to setup

Setup now lists existing workspaces on the server and prompts the user
to pick one (or create new) instead of silently defaulting to
"claude_code". Also asks for / confirms the peer name -- defaults from
the OS username, but re-runs surface the existing config value so users
don't accidentally lose customizations.

New module src/workspaces.ts hits POST /v3/workspaces/list directly via
fetch instead of going through the SDK. The SDK's Honcho client memoizes
a get-or-create call on the configured workspaceId, which would
materialize a workspace just for asking the list -- that's wrong UX
when we're trying to discover what already exists.

New runner src/skills/list-workspaces-runner.ts emits the workspace list
as JSON for the setup skill to consume. SKILL.md gains a step 5 between
"API key set" and "validate" that:
- Reads OS username + existing peerName from config as defaults
- Asks for peer name confirmation
- Calls list-workspaces-runner and branches on count (0 / 1 / >1)
- Presents a picker including a "create new" option
- Persists both values to ~/.honcho/config.json via env-var pass-through

Verified against a live Honcho 3.0.5 deployment with 3 workspaces.

Author: offendingcommit

plugins/honcho/build.ts

@@ -18,6 +18,7 @@ const entrypoints = [
   "src/skills/setup-runner.ts",
   "src/skills/status-runner.ts",
   "src/skills/health-runner.ts",
+  "src/skills/list-workspaces-runner.ts",
 ];
 
 const result = await Bun.build({