Add mission approval inbox readbacks

[uesugitorachiyo]

Summary

• add read-only ao-command mission approvals list/detail readbacks
• add a safe mission approval inbox fixture with pending, approved, and denied records
• cover CLI list/detail JSON behavior and no-authority flags in tests

Verification

• go test ./internal/cli -run TestMissionApprovalInboxListAndDetailReadbacks -count=1
• go test ./... -count=1
• go vet ./...
• go build ./cmd/ao-command
• git diff --check
• scripts/ao-command-smoke.sh --forge ../ao-forge --foundry ../ao-foundry --out tmp/month6-node-02-smoke
• scripts/production-readiness-audit.sh --skip-remote-admin --out tmp/month6-node-02-production-readiness.json

Safety: read-only Command readback only; no approval grant, execution, provider call, credential use, dependency update, release, publish, tag, promotion, or RSI claim.