[FEATURE] Allow sharing/co-management of scheduled routines (remote agents) with teammates

Problem Statement

Scheduled routines (Claude Code remote agents created via /schedule or the remote-trigger API) are currently single-owner. The GET /v1/code/triggers/{id} response exposes only a creator field — there is no shared_with, collaborators, or members field.

This causes a real workflow problem for teams:

• I built an autonomous routine that runs daily on my team's behalf (auto-closes Jira tickets when their linked dev ticket is "Done", and posts a notification to a shared Slack channel).
• The routine is genuinely a team asset — my QA Lead and another QA engineer need to be able to view its run history, tweak its prompt, pause/resume it, and trigger manual runs when they're investigating something — without having to ping me every time.
• Today I'm the only person who can manage it. If I'm on PTO or change roles, the team is blocked.

Proposed Solution

Add a sharing/permissioning layer to routines, similar to how Google Docs or shared Anthropic Console workspaces work. Concretely:

1. A shared_with (or collaborators) field on the routine object listing user account UUIDs and a role (viewer | editor | owner).
2. API endpoints to add/remove collaborators:

• POST /v1/code/triggers/{id}/collaborators
• DELETE /v1/code/triggers/{id}/collaborators/{account_uuid}

1. UI affordance on https://claude.ai/code/routines/{id} to "Share with teammate" — paste an email or pick from org members.
2. Roles:

• Viewer: can see run history and the prompt; cannot edit or run.
• Editor: can edit prompt / schedule / MCP connections; can trigger manual runs.
• Owner: same as Editor + can add/remove collaborators or transfer ownership.

Routine still executes with a single set of credentials (probably the creator's, or an org-scoped service identity if/when that exists), so this is purely a management-plane permission.

Alternative Solutions

• Each teammate creates their own copy of the routine → causes triple execution against the same Jira tickets (race conditions, triple Slack pings). Not viable.
• Shared service account on claude.ai with shared credentials → works but is fragile (2FA, password rotation, audit trail loss) and requires an extra paid seat.
• Just share the routine config via a doc and re-create on demand → what I'm doing today, but it means the team can't actually interact with the live routine.

Priority

High — Significant impact on productivity

Additional Context

Use case: an "auto-close Jira PS ticket on linked dev ticket Done" routine running daily for the QA team. Three QA members need to manage it; today only one can.