feat(status): add setup readiness report

[codeaholicguy]

Summary

• add a canonical ai-devkit status readiness report with JSON and shared-table human output
• cover the 10 approved setup checks across Codex, Pi, Claude, tmux, channels, registries, version, and project config
• keep missing state reportable, isolate probe failures, and redact credentials and raw errors
• add lifecycle requirements, design, planning, implementation, and testing documentation

Validation

• npm run build — 6 projects passed
• npm test — 6 targets, 1,984 tests passed
• npm run lint — 0 errors; 4 pre-existing warnings outside changed files
• targeted status tests — 2 files, 7 tests passed
• CLI coverage — 88 files / 1,057 tests; status service 91.24% statements and 92.14% lines
• npx ai-devkit@latest lint — passed
• npx ai-devkit@latest lint --feature status-cmd — passed
• built JSON and human command smoke checks — passed

Scope exclusions

No live agent list, full capacity detail, skill-index freshness, session inventory, worktree/Git inventory, task or memory state, channel network probes, registry reachability, or general environment inventory.