feat: add description (D) mode

[jooyoungseo]

Feature Request

Description

Add Description (D) mode where users can find the basic summary of the current plot. also, add a data table along with the description.

Motivation

This is based on our users' feedback. Although AI features are instrumental, we need to provide a minimum-threshold summary and description of the current plot by leveraging JSON metadata. The description needs to include some statistical characteristics, trends, shapes, and data table. This does not require AI APIs.

Proposed Solution

Per plot type, provide description and summary.

Additional Context

N/A

Checklist

• [x] I have searched for similar feature requests and confirmed that this is a new request.
• [x] I have provided a clear and concise description of the feature.
• [x] I have explained the motivation behind this feature request.
• [x] I have outlined a proposed solution or ideas for implementing this feature.
• [x] I have provided any additional context or screenshots if applicable.