fix(cli): treat async accepted sends as success

[jiashuoz]

Summary

• report normal async accepted send and reply results as successful CLI outcomes
• reserve exit 3 exclusively for pending_review holds
• add frozen exit 7 for terminal failed and unknown persisted outcomes so callers inspect the returned message id instead of risking a duplicate retry

Test plan

• npm test --workspace @e2a/cli (112 passed)
• npm run build --workspace @e2a/cli