[External State] squad copilot reads and writes local state only #1397

Summary

squad copilot updates team roster in local .squad/team.md and does not follow externalized state.

Evidence

• packages/squad-cli/src/cli/commands/copilot.ts:30-31,38
  • uses detectSquadDir(dest), then readTeamMd(squadDir)
• packages/squad-cli/src/cli/core/team-md.ts:13-15,28-30
  • readTeamMd/writeTeamMd operate directly on <squadDir>/team.md
• No external-state resolution helper in call chain.

Expected

Roster edits should target effective state dir when externalized.

Actual

Roster edits target local .squad/team.md.