feat: add attachment upload and delete commands

[pchuri]

Pull Request Template

Description

Add attachment upload and delete commands with client support, tests, and documentation. Closes #35.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring

Testing

• Tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

Screenshots (if applicable)

N/A

Additional Context

Closes #35.

[Copilot]

Pull request overview

Adds CLI and client support for uploading and deleting Confluence page attachments, with accompanying tests and README updates to complete the attachment lifecycle feature requested in #35.

Changes:

• Added uploadAttachment and deleteAttachment methods to ConfluenceClient (multipart upload + delete endpoint).
• Added attachment-upload and attachment-delete CLI commands.
• Added unit tests and README documentation; introduced form-data dependency.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/confluence-client.js	Implements multipart attachment upload (with X-Atlassian-Token) and attachment delete support in the client.
bin/confluence.js	Exposes new attachment upload/delete commands in the CLI.
tests/confluence-client.test.js	Adds test coverage for multipart upload behavior, PUT vs POST, and delete endpoint usage.
package.json	Adds form-data runtime dependency needed for multipart uploads.
package-lock.json	Updates lockfile to include form-data (but currently has a version mismatch vs package.json).
README.md	Documents new commands and updates feature list/command table.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

🎉 This PR is included in version 1.17.0 🎉

The release is available on:

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

Your semantic-release bot 📦🚀