Replaces the Task 31 stub README with complete documentation:
quickstart, first-time setup (invite flagging, seeding, smoke),
usage examples for all three watch modes, CLI flag reference, env
var table, scenario descriptions, error handling summary, test
account filtering explanation, and architecture overview.
Adds CHECKLIST.md with post-deploy verification, bring-up,
scenario, watch mode, failure handling, and staging gate items.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
d5194f43ba