task: #3609161 Update Drupal core to ~11.4.0

Bumps the Drupal core requirement on the 10.1.x branch to match the rest of the Varbase 10.1.x suite, which has already moved to ~11.4.0.

Related issue: https://www.drupal.org/project/varbase_media_demo/issues/3609161

What / why

• composer.json: "drupal/core": "~11.3.0" → "~11.4.0"
• varbase_media_demo.info.yml: core_version_requirement: ~11.3.0 → ~11.4.0

With the branch still on ~11.3.0, Composer cannot resolve drupal/varbase_media_demo:dev-10.1.x on a fresh Varbase 10.1.x-dev (Drupal 11.4) build and silently falls back to the stale 10.1.0-alpha1 tag, which ships the old dead-Vimeo demo content and fails media oEmbed validation on install.

AI-Generated: Yes (Claude Code drafted this composer.json/info.yml core-version bump; reviewed by Rajab Natshah.)

Checkpoints

• File an issue about this project
• Addition/Change/Update/Fix to this project
• Testing to ensure no regression
• Automated unit/functional testing coverage
• Developer Documentation support on feature change/addition
• User Guide Documentation support on feature change/addition
• UX/UI designer responsibilities
• Accessibility and Readability
• Reviewed by a human
• Code review by maintainers
• Full testing and approval
• Credit contributors
• Review with the product owner
• Update Release Notes
• Release