[w21180239]

Summary

• Add --format <json|text> to message get and message list (default json, unchanged).
• text prints one line per message: local time, author (resolved display/real name with --resolve-users, else user/bot id), [reply] for thread replies in channel history, content with newlines collapsed.
• Replaces the ad-hoc json | python3 -c ... one-liners agents keep writing to skim a channel.

Thread-mode (--thread-ts/URL) output omits thread_ts, so no [reply] marker there.

Test plan

• bun test (404 pass, incl. new test/message-text-format.test.ts)
• bun run typecheck, bun run lint (0 errors), bun run format:check

🤖 Generated with Claude Code

[w21180239]

Ready for review: mergeable, current with main (0 commits behind), no outstanding review comments.

Verified locally on Windows: bun run lint, bun run format:check, bun run typecheck pass; bun test test/message-text-format.test.ts 5 pass.

CI: run 39334511756 is action_required -- GitHub requires a maintainer to approve workflow runs for fork PRs, so the jobs never started and I cannot re-trigger them.