Add Dependabot configuration and dependency submission workflow

[Shashankpgit]

Summary

• Enables Dependabot to automatically open weekly PRs for npm dependencies in / and /deploy, as well as GitHub Actions workflow versions, keeping the dependency graph and security
  alerts up to date.
• Adds a dependency-submission workflow that reports transitive npm dependency graphs to GitHub before Dependabot runs each Monday, ensuring Dependabot has complete visibility —
  including the deploy/ package that has no committed lock file.
• Dependencies are grouped by ecosystem (Sunbird packages, Gulp/Webpack tooling, Karma/Jasmine testing, ESLint) to reduce PR noise.

Changes

• .github/dependabot.yml — Configures three Dependabot ecosystems: npm at /, npm at /deploy, and github-actions at /. Weekly schedule on Mondays at 03:30 UTC, with grouped update
  rules to batch related packages together.
• .github/workflows/dependency-submission.yml — Runs npm-dependency-submission-action for both the root and deploy/ packages. Triggers on schedule (Monday 03:00 UTC), on pushes/PRs
  to master that touch package*.json, and manually via workflow_dispatch. Generates a transient lock file for deploy/ since none is committed.

How to Test

1. Merge this PR and navigate to the repository's Insights → Dependency graph tab — both package.json files should appear within ~10 minutes after the workflow runs.
2. Trigger the workflow manually: Actions → Dependency Submission → Run workflow and confirm it completes without errors.
3. Wait until the next Monday or manually trigger a Dependabot run from Insights → Dependency graph → Dependabot to confirm PRs are opened with the correct labels and grouped
   commits.
4. Verify that a chore(deps) PR is opened for npm packages and a chore(ci) PR is opened for any outdated GitHub Actions.

Checklist

• Tests added or updated
• Documentation updated (if public API or behavior changed)
• No breaking changes — or breaking changes noted with ! in title and explained in Summary
• Reviewed my own diff before requesting review

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