feat: Team status dashboard for multi-user environments

[nigel-dev]

Source

Audit report — Section 9: Phase 3 Roadmap

Description

MC is currently single-user — one developer's jobs on one machine. In team environments, multiple developers may be running MC jobs on the same repository, with no visibility into each other's work.

Proposed Solution

1. Shared state: Optional shared state backend (file-based in shared directory, or lightweight server) for multi-user visibility
2. User attribution: Tag jobs with the user who launched them
3. Team dashboard: mc_team tool showing all team members' active jobs
4. Conflict detection: Warn when two users have jobs touching the same files
5. Merge coordination: Prevent simultaneous merges to the same branch

Priority

P3 — long-term feature. Current single-user model works well for individual developers. Team features become relevant when MC is adopted across a team.