Adds MODE=compose|swarm. Each instance owns one Docker daemon and runs
one paradigm; see docs/superpowers/specs/2026-08-04-multi-server-fanout-design.md
for why this exclusivity is the intended design.
Blocking a user prevents them from interacting with repositories, such as opening or commenting on pull requests or issues. Learn more about blocking a user.
Design spec for the master/agent architecture and the implementation plan for phase 1 (#6). Docs only, no code.
Milestone: Master/agent (#6–#10).