feat: add thread deletion support

[scottlovegrove]

Summary

• Adds tw thread delete <thread-ref> command with --yes confirmation, --dry-run, and --json flags
• Batch-fetches thread and session user to validate ownership before deletion
• Uses process.exitCode = 1 + return (not process.exit(1)) to avoid leaving the early spinner stuck

Closes #130

Test plan

• npm run type-check passes
• All 342 tests pass (npm test)
• Lint clean (npm run lint)
• Skill file in sync (npm run check:skill-sync)
• Manual: tw thread delete <own-thread-url> shows confirmation prompt
• Manual: tw thread delete <own-thread-url> --yes deletes the thread
• Manual: tw thread delete <other-user-thread-url> --yes shows ownership error

🤖 Generated with Claude Code

[doistbot]

This PR introduces the tw thread delete command complete with confirmation safeguards, dry-run capabilities, and ownership validation, which is a great addition to our thread management tools. The careful approach to handling early spinner exits and verifying permissions ensures a safe foundation for destructive actions. A few adjustments have been flagged regarding the ordering of validation checks—specifically moving the dry-run check before network calls and prioritizing the public channel guard—along with refining the --json flag's behavior during preview and unconfirmed states to guarantee reliable scriptability.

_{Share Feedback • Review Logs}

[doist-release-bot]

🎉 This PR is included in version 2.23.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[rmartins90]

✅