[SEO] Enable webpack bundle analyzer for FCP optimization

[megha1807]

Description
This PR conditionally enables the webpack bundle analyzer to help analyze bundle size and improve performance metrics such as First Contentful Paint (FCP).

Changes Made
Added conditional configuration for gatsby-plugin-webpack-bundle-analyser-v2 in gatsby-config.js.
The plugin now runs only when the ANALYZE_BUNDLE environment variable is set, ensuring that regular builds remain unaffected.
This allows developers to inspect the webpack bundle composition and identify optimization opportunities.

Files changed
gatsby-config.js

How to test
Run the project locally using npm run develop or npm start.
Set the environment variable ANALYZE_BUNDLE=true and run the build command.
The webpack bundle analyzer server should open automatically and display the bundle size visualization.

Related issue
Fixes #7157

Signed commits

• Yes, I signed my commits.

[l5io]

🚀 Preview for commit 166b997 at: https://69b188b2ba333400992d0d23--layer5.netlify.app

[leecalcote]

Thank you for this, @megha1807. You know what would accompany this enhancement well?

A new make target: make site-analyze, in which this new env var is enabled.

[megha1807]

Thanks for the suggestion @leecalcote ! I’ll add a new make site-analyze target with the env var enabled and push an update shortly.

[l5io]

🚀 Preview for commit 447c1fb at: https://69b2316c420b024e953b5278--layer5.netlify.app