chore(deps): group react and react-dom in dependabot config

[sserrata]

Summary

React enforces exact version parity between react and react-dom at runtime. When Dependabot bumps them independently, the demo build fails with:

Incompatible React versions:
  - react:     19.2.3
  - react-dom: 19.2.4

Adding a groups config ensures Dependabot always bumps react and react-dom together in a single PR.

Closes #1336

Test plan

• Verify Dependabot opens a single grouped PR for the next react/react-dom update

🤖 Generated with Claude Code

[github-actions]

Size Change: 0 B

Total Size: 2.2 MB

ℹ️ View Unchanged

Filename	Size
demo/.docusaurus/codeTranslations.json	2 B
demo/.docusaurus/docusaurus.config.mjs	14.7 kB
demo/.docusaurus/globalData.json	65.4 kB
demo/.docusaurus/i18n.json	372 B
demo/.docusaurus/registry.js	94.7 kB
demo/.docusaurus/routes.js	89.6 kB
demo/.docusaurus/routesChunkNames.json	37.1 kB
demo/.docusaurus/site-metadata.json	1.51 kB
demo/build/assets/css/styles.********.css	163 kB
demo/build/assets/js/main.********.js	656 kB
demo/build/assets/js/runtime~main.********.js	22.3 kB
demo/build/index.html	97.6 kB
demo/build/petstore/add-pet/index.html	29.3 kB
demo/build/petstore/create-user/index.html	24 kB
demo/build/petstore/create-users-with-array-input/index.html	24.1 kB
demo/build/petstore/create-users-with-list-input/index.html	24.1 kB
demo/build/petstore/delete-order/index.html	23.8 kB
demo/build/petstore/delete-pet/index.html	24.1 kB
demo/build/petstore/delete-user/index.html	24.3 kB
demo/build/petstore/find-pets-by-status/index.html	24.8 kB
demo/build/petstore/find-pets-by-tags/index.html	25.4 kB
demo/build/petstore/get-inventory/index.html	23.1 kB
demo/build/petstore/get-order-by-id/index.html	24.1 kB
demo/build/petstore/get-pet-by-id/index.html	24.9 kB
demo/build/petstore/get-user-by-name/index.html	24.4 kB
demo/build/petstore/login-user/index.html	24.9 kB
demo/build/petstore/logout-user/index.html	23.7 kB
demo/build/petstore/new-pet/index.html	24.3 kB
demo/build/petstore/pet/index.html	22.5 kB
demo/build/petstore/place-order/index.html	23.3 kB
demo/build/petstore/schemas/apiresponse/index.html	24.6 kB
demo/build/petstore/schemas/cat/index.html	38.8 kB
demo/build/petstore/schemas/category/index.html	25.7 kB
demo/build/petstore/schemas/dog/index.html	39 kB
demo/build/petstore/schemas/honeybee/index.html	39.1 kB
demo/build/petstore/schemas/id/index.html	22.7 kB
demo/build/petstore/schemas/order/index.html	26.8 kB
demo/build/petstore/schemas/pet/index.html	38.6 kB
demo/build/petstore/schemas/tag/index.html	24.1 kB
demo/build/petstore/schemas/user/index.html	40.7 kB
demo/build/petstore/store/index.html	21.5 kB
demo/build/petstore/subscribe-to-the-store-events/index.html	30.2 kB
demo/build/petstore/swagger-petstore-yaml/index.html	30.2 kB
demo/build/petstore/update-pet-with-form/index.html	24.3 kB
demo/build/petstore/update-pet/index.html	24.7 kB
demo/build/petstore/update-user/index.html	24.3 kB
demo/build/petstore/upload-file/index.html	24.1 kB
demo/build/petstore/user/index.html	22.2 kB

_{compressed-size-action}

[github-actions]

Visit the preview URL for this PR (updated for commit b58899d):

https://docusaurus-openapi-36b86--pr1341-dr2oau44.web.app

_{(expires Sat, 25 Apr 2026 15:49:05 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: bf293780ee827f578864d92193b8c2866acd459f}