[Feature]: run any Claude/Codex subscription on any workspace, from the CLI #26875

Problem or use case

I want to run any of my Claude (or Codex) subscriptions on any workspace, on one machine or across several Orca hosts. For example, a work subscription and a personal one, or spreading a batch of agent workspaces across subscriptions so none hits its limit.

Today that needs a person in the Orca app. orca account list shows the saved accounts, but no CLI command switches between them: orca account select only accepts OpenCode and Devin. A script or coordinating agent that creates workspaces with orca worktree create --agent claude cannot choose which subscription they run on, and headless hosts (orca serve) have no switcher at all.

Proposed solution

1. CLI account switching (feat(cli): select the Claude or Codex account from orca account select #26870): orca account select --agent claude|codex --account <id|email|system>, using the existing accounts.selectClaude / accounts.selectCodex runtime methods. Also print account ids in orca account list.
2. Parallel subscriptions on one machine: per-account Claude folders, so each workspace keeps the account it started with. They were reverted before release in Revert Claude per-account folders (#24434, #26405) before release #26638 and are being re-landed in Re-land Claude per-account folders (#24434, #26405) with the upgrade and proxy fixes #26801.

How much each step covers:

Alternatives or additional context

• (1) alone is useful but partial on current main. The full goal needs (2) as well.
• On a build from just before Revert Claude per-account folders (#24434, #26405) before release #26638, (1) already gives the full behaviour: two workspaces on one machine ran on two different Claude subscriptions at the same time.
• A per-workspace --account flag on worktree create is a natural follow-up once Re-land Claude per-account folders (#24434, #26405) with the upgrade and proxy fixes #26801 lands.
• The same choice belongs in the UI: an account picker in the new-workspace dialog, next to the agent picker, so a person creating a workspace can pick its subscription without switching the global account first. The CLI flag and the UI picker would share one per-workspace binding. Related: [Feature]: Per-worktree account pinning — run different Claude/Codex accounts concurrently #9496 (per-worktree pinning / account picker at launch), [Feature]: Add per-project and per-worktree account assignment for token and credit management #7782 (per-project and per-worktree assignment), and [Feature]: Per-worktree Claude account binding (concurrent multi-account + per-project defaults) #6921 (closed; its PR feat: per-worktree Claude account binding (concurrent multi-account) #6963 was closed unmerged).