Fix ESLint and Stylelint violations

[jjroelofs]

Summary

Running the project linters locally reveals violations that should be fixed.

Stylelint (6 errors): Long-form hex colors in scss/base/variables.scss that should use shorthand (#222222 → #222, #333333 → #333, etc.).

ESLint (36 errors): Prettier formatting violations in Gruntfile.js, postcss.config.js, and webpack.config.js (single quotes → double quotes, formatting). Plus 3 rule violations requiring inline disables for standard config file patterns.

Scope of affected files

• scss/base/variables.scss
• Gruntfile.js
• postcss.config.js
• webpack.config.js