Configure Netlify build settings per deploy context in netlify.toml ([build] and [context.*] blocks)

Documented steps

1. Auth: None required to write the file; a connected Netlify site is needed for the settings to apply on deploy
2. Add a netlify.toml file in the root of your site repository (or use base for monorepos)
3. Define global build settings in the top-level [build] block: base = "project/", publish = "build-output/", command = "yarn build", environment = { NODE_VERSION = "18" }
4. Override settings for production-branch deploys with [context.production], e.g. publish = "output/", command = "make publish"
5. Override settings for pull/merge-request deploys with [context.deploy-preview], including nested [context.deploy-preview.environment] for preview-only env vars
6. Override settings for non-production branch deploys with [context.branch-deploy], and for one specific branch use [context.<branch-name>] (e.g. [context.staging])
7. Control local netlify dev behavior with [context.dev] / [context.dev.environment]
8. Enable build plugins with [[plugins]] package = "@netlify/plugin-lighthouse", and post-processing like Pretty URLs with [build.processing.html] pretty_urls = true
9. Deploy and confirm which context/settings applied in the Deploys tab build log (Netlify announces the resolved context and settings at the start of the build)
10. Official docs: https://docs.netlify.com/build/configure-builds/file-based-configuration/