Add GitHub Actions for Dart CI and update status badges in README.md

[codevalley]

We need to set up Continuous Integration (CI) for this project using GitHub Actions and reflect the build/test status in the README.md file using appropriate status badges.

This will help:

• Automatically verify code quality on push/PR.
• Increase contributor confidence.
• Improve project visibility via status badges.

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Tasks:

• Create a GitHub Actions workflow for Dart CI (analyze, format, test).
• Ensure the workflow runs on push and pull_request.
• Add build status badge to README.md.
• (Optional) Add coverage or test result badge if applicable.

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Resources:

• [Dart GitHub Actions guide](https://dart.dev/guides/ci/github-actions)
• [Example Workflow File](https://github.com/dart-lang/setup-dart)
• [Shields.io for README badges](https://shields.io/)

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Additional Notes:

• This issue is open for first-time contributors.
• Please comment if you would like to work on this.
• Make sure to follow existing code style and open a PR when ready.