refactor: use meteor tokens

[larskemper]

resolves #12584

[Copilot]

Pull Request Overview

This PR refactors the SwagMigrationAssistant module to use Meteor design token variables instead of hardcoded values and legacy SCSS variables, improving design system consistency. The changes also include UI improvements and some component cleanup.

• Replace hardcoded font sizes, colors, and spacing with Meteor design token CSS variables
• Update stylelint configuration to enforce Meteor token usage as errors instead of warnings
• Add missing translation strings and improve empty state presentations

Reviewed Changes

Copilot reviewed 37 out of 37 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Resources/app/administration/stylelint.config.mjs	Updates Meteor token rules from warnings to errors
src/Resources/app/administration/src/module/swag-migration/snippet/*.json	Adds new translation strings for empty states
src/Resources/app/administration/src/module/swag-migration/page/**/*.scss	Converts legacy SCSS variables to Meteor design tokens for colors, fonts, and spacing
src/Resources/app/administration/src/module/swag-migration/component/**/*.scss	Replaces hardcoded values with Meteor token variables
src/Resources/app/administration/src/module/swag-migration/component/swag-migration-expand-div/	Removes unused expand div component
.gitlab/	Removes GitLab CI configuration files

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