feat: ADAPT-3748 theme settings implementation

[Vaahwan]

✅ PR Completion Checklist

• PR title follows format: Prefix: ADAPT-XXXX Brief description

  e.g. Feature: ADAPT-3648 Deprecate legacy plugins · Bugfix: ADAPT-2504 Failed import creates rogue course

• JIRA ID linked in the Context section below
• Plugin version updated in bower.json (if applicable)
• npm run test-e2e-dev-pipeline executed and passing
• No new issues reported by SonarLint (attach screenshot if applicable)
• Own diff reviewed before requesting review
• At least two reviewers added (Copilot set as default)

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Context

Resolves / Addresses ADAPT-XXXX

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Description

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Changes in the codebase

path/to/file.ext

path/to/file.ext

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