chore(ci): Add Dependabot configuration for GitHub Actions and npm dependencies

[hristoterezov]

Summary

• Adds comprehensive Dependabot configuration to automate dependency updates
• Enables GitHub Actions version monitoring with weekly updates
• Configures npm dependency updates with grouped dev dependencies to reduce PR noise
• Uses conventional commit message formatting for consistency

Configuration Details

GitHub Actions Monitoring

• Weekly schedule for action version updates
• Labels: dependencies, github-actions
• Commit prefix: chore(ci)

npm Dependencies

• Weekly schedule for package updates
• Labels: dependencies, npm
• Commit prefix: build(deps) (matches existing Dependabot PRs)
• Groups minor and patch updates for development dependencies to reduce PR volume

Benefits

• Automated version updates for GitHub Actions workflows
• Improved npm dependency monitoring with better organization
• Consistent commit message formatting
• Reduced PR noise through grouped updates

Test Plan

• Configuration file created at .github/dependabot.yml
• Once merged, Dependabot will start creating PRs on the weekly schedule
• Verify that GitHub Actions and npm updates appear with correct labels and commit messages