[codex] Configure team state owner

[yibeichan]

Summary

• replace the hardcoded team.* state owner with SCHIST_TEAM_OWNER
• update MCP tool and CLI descriptions to remove deployment-specific owner names
• document SCHIST_TEAM_OWNER and add regression coverage for configured, missing, and mismatched team owners

Root cause

agent_state namespace validation hardcoded owner=eleven for team.* keys. That made the shared team namespace unusable for deployments whose coordinator agent has a different identity and leaked a deployment-specific name through public tool descriptions.

Validation

• npm run build
• npm test -- --testPathPatterns=memory.test.ts memory-cli.test.ts
• npm test

Closes #195