[Sistent] Add BBChart component to the sistent components page

Current Behavior

Layer5 and its projects use the Sistent library to enable component reuse across various projects.
The BBChart (Billboard.js chart wrapper) is the primary charting component available in Sistent, but it is currently not represented in the centralized Sistent component documentation at https://layer5.io/projects/sistent/components.
Adding documentation for BBChart will provide a clear reference for its usage, guidelines, and examples, helping developers understand and reuse the component consistently across Layer5 projects.

Desired Behavior

Add proper documentation for the BBChart component, following the same structure used by other documented Sistent components.
The documentation should follow the new Sistent MDX documentation structure by creating the following files under:
src/collections/sistent/components/bb-chart/

• index.mdx: Overview of the BBChart component for data visualization and telemetry dashboards.
• guidance.mdx: Chart options, light/dark theme integration, tooltips, and time-series axes configuration.
• code.mdx: Code examples demonstrating line, bar, area, gauge, and donut charts using <ThemeWrapper> and <CodeBlock>.

The completed documentation should be available on the Sistent components page and provide a centralized reference for developers using BBChart.

Environment:

• Host OS:
• Browser:

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