chore: update changelog and version to 0.3.4

[benym]

✨ Summary

🎯 Scope

• CLI commands (init, status, doctor, update)
• Core installer / platform detection
• Comet skills (assets/skills/, assets/skills-zh/)
• Comet shell scripts (assets/skills/comet/scripts/)
• Tests / CI
• Documentation / changelog
• Other:

🧪 Testing

• pnpm build
• pnpm lint
• pnpm format:check
• pnpm test
• pnpm test -- test/ts/comet-scripts.test.ts
• pnpm test:shell
• Not run:

✅ Checklist

• PR title follows Conventional Commits, for example fix: handle project-scope init
• User-facing behavior is documented in README.md, README-zh.md, or CONTRIBUTING.md
• CHANGELOG.md is updated when behavior changes
• Skill changes were made in Chinese first when applicable, then synced to English
• New scripts are included in assets/manifest.json and relevant tests
• Shell scripts remain portable across macOS, Linux, and Windows Git Bash
• No unrelated generated files or local artifacts are included

👀 Notes for Reviewers

[gemini-code-assist]

Code Review

This pull request bumps the package version from 0.3.3 to 0.3.4 in package.json and package-lock.json, and updates the CHANGELOG.md with the release notes for version 0.3.4. There are no review comments, and I have no feedback to provide.