Configure bundle analysis and track package size

[yuribodo]

Description

Since users copy components into their projects, individual component file sizes matter. There is currently no visibility into bundle size or size regressions.

Tasks

• Set up `@next/bundle-analyzer` for the docs site
• Add a script or CI step that reports byte size of each chart component
• Set up size-limit or bundlewatch for tracking regressions
• Document component sizes in README or docs
• Add bundle size badge to README

Why this matters

Prevents dependency creep and gives contributors visibility into size regressions when adding features.