Integrate cssnano for CSS optimization

[Copilot]

Adds cssnano to the PostCSS pipeline to optimize CSS output in production and staging builds.

Changes

• esbuild.js: Added getPostcssPlugins(env) function that conditionally includes cssnano based on build environment
  • Production/staging: Applies cssnano with comment removal preset
  • Development: Skips cssnano to preserve readable CSS for debugging
• package.json: Added cssnano@7.1.2 as dev dependency

Example

const getPostcssPlugins = (env) => {
  const plugins = [postcssUrl({ /* ... */ })]
  
  if (env === "production" || env === "staging") {
    plugins.push(cssnano({
      preset: ['default', { discardComments: { removeAll: true } }]
    }))
  }
  
  return plugins
}

Impact

CSS file sizes reduced by ~7% (e.g., carousel: 82K → 76K) through minification, duplicate rule merging, and value optimization.

Warning

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I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

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Original prompt

Incorporate cssnano

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[Copilot]

Pull Request Overview

This PR integrates cssnano into the build pipeline to optimize CSS output in production and staging environments. The implementation conditionally applies CSS minification based on the build environment, reducing file sizes by approximately 7% while preserving readable CSS during development.

Key changes:

• Created environment-aware PostCSS plugin configuration with conditional cssnano optimization
• Added cssnano package dependency for CSS minification capabilities

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
packages/widget-utils	Updated subproject commit reference
package.json	Added cssnano v7.1.2 as development dependency
esbuild.js	Refactored PostCSS configuration into getPostcssPlugins() function with conditional cssnano integration