fix: update webpack CLI flags for v6/v5 compatibility in grid-lite styling sample

[Copilot]

Fixed build errors caused by deprecated webpack CLI v6 and webpack-dev-server v5 flags in the grid-lite styling-custom-theme sample.

Changes

• Webpack CLI v6 compatibility

  • Updated --env.KEY=value → --env KEY=value syntax
  • Removed deprecated --display-error-details flag

• Webpack-dev-server v5 compatibility

  • Replaced --content-base → --static flag

Example

// Before
"build:prod": "webpack --env.NODE_ENV=production --display-error-details --bail"

// After  
"build:prod": "webpack --env NODE_ENV=production --bail"

The sample now builds successfully with SCSS processing via sass-loader working as intended.

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