Add Dependabot configuration for Composer, npm, and GitHub Actions

[Copilot]

This adds a standard Dependabot v2 configuration for the dependency ecosystems already used in the repository, with all update PRs targeting master. The config covers Composer, npm, and GitHub Actions on a weekly schedule.

• Dependabot configuration

  • Add .github/dependabot.yml
  • Set version: 2
  • Configure updates for:
    • composer in /
    • npm in /
    • github-actions in /

• PR targeting

  • Set target-branch: master for each ecosystem so automated dependency update PRs are opened against the repository’s base branch

• Schedule

  • Use a conventional weekly cadence for all update entries

version: 2updates:
- package-ecosystem: composerdirectory: /schedule:
interval: weeklytarget-branch: master
- package-ecosystem: npmdirectory: /schedule:
interval: weeklytarget-branch: master
- package-ecosystem: github-actionsdirectory: /schedule:
interval: weeklytarget-branch: master