Add calculator Datadog app

[setnilson]

Summary

Builds the requested calculator experience as a new Datadog App workspace at apps/sarah-s-app-tue-aug-18-3-34-53-pm so it can be developed, built, and uploaded independently.

Changes

• Scaffolded apps/sarah-s-app-tue-aug-18-3-34-53-pm as a Vite React Datadog App.
• Replaced the default welcome screen with a responsive calculator supporting digits, decimal input, sign toggle, percent, delete, clear, chained operators, equals, and divide-by-zero error handling.
• Added scoped calculator styling and fixed app metadata/site resolution in vite.config.ts to use the workspace Datadog site fallback.
• Regenerated the root package-lock.json so the new workspace package and node_modules workspace link are represented.

Testing/Validation

• npm install --package-lock-only --ignore-scripts
• npm ci --ignore-scripts
• Verified package-lock.json contains apps/sarah-s-app-tue-aug-18-3-34-53-pm and node_modules/sarah-s-app-tue-aug-18-3-34-53-pm workspace link entries.
• npm run typecheck -w apps/sarah-s-app-tue-aug-18-3-34-53-pm
• npm run lint -w apps/sarah-s-app-tue-aug-18-3-34-53-pm
• npm run build -w apps/sarah-s-app-tue-aug-18-3-34-53-pm
• Ran the Vite dev server and used Playwright to assert 12 + 7 = 19, then captured desktop and mobile screenshots.

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PR by Bits - View session in Datadog

Comment @datadog-staging to request changes

[datadog-staging]

View session in Datadog

Bits Code status: ✅ Done

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[datadog-staging]

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