feat: add support for generating pptx files via PptxGenJS (Issue #915)

[aviralgarg05]

Description

This pull request implements support for generating PowerPoint (.pptx) documents using the PptxGenJS library, addressing the requirements outlined in issue #915.

Since PptxGenJS is a JavaScript-based library and the core document agent operates in a Python environment, this PR introduces a hybrid integration:

1. Node.js Bridge: Added a new script scripts/generate_pptx.js that acts as a wrapper for the pptxgenjs library. It handles the creation of slides, including titles, headings, bullet points, and tables from a structured JSON payload.
2. Toolkit Update: Modified the PPTXToolkit in the backend to override the default generation logic. It now serializes the document content and executes the Node.js script via a subprocess.
3. Dependency Management: Added pptxgenjs to the root package.json.

Technical Implementation Details:

• Robust Path Resolution: Refactored pptx_toolkit.py to use pathlib.Path and a _get_project_root() helper, ensuring the Node.js bridge is located correctly across different environments.
• Styling & Theming: Introduced a central THEME configuration object in generate_pptx.js to manage colors, font sizes, and layout in one place, making it easier to customize the look and feel of generated presentations.
• Unit Testing: Added comprehensive unit tests in backend/test/utils/toolkit/test_pptx_toolkit.py to verify path resolution, subprocess execution, and JSON serialization logic.

This allows the Document Agent to create high-quality, professional PowerPoint presentations while maintaining compatibility with the existing Python orchestration layer.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Visual Reference

[lightaime]

Thanks @aviralgarg05 for the PR! We wonder if it is possible to move the PPTXGenjs support to the CAMEL repo: https://github.com/camel-ai/camel. Some other agent builders can also use it early for their applications 🙏

[aviralgarg05]

Thanks @aviralgarg05 for the PR! We wonder if it is possible to move the PPTXGenjs support to the CAMEL repo: https://github.com/camel-ai/camel. Some other agent builders can also use it early for their applications 🙏

I have created it there

[Wendong-Fan]

thanks for the contribution! could @bytecraftii @fengju0213 help reviewing this?

[bytecii]

Left some comments. And can we also add a unit test for this?

[bytecii]

Can we also include a snapshot of created slide in the description for future reference and a more detailed description? Thanks.

[aviralgarg05]

Can we also include a snapshot of created slide in the description for future reference and a more detailed description? Thanks.

I'll update the PR description with more technical implementation details. I'll also generate a sample PPTX and attach a snapshot of the slides to the description for better reference.

[4pmtong]

Thanks @aviralgarg05 for contribution!