feat: reconcile when saving to firebase

[dwelle]

• rewritten how saving to firebase works:
  • we no longer overwrite remote (firestore) data with ours, but instead reconcile both states. This will ensure that if there's an issue where local version doesn't contain latest data despite sceneVersion being larger, no data is lost.
  • we no longer bail when firestore sceneVersion is larger than ours. Instead we always reconcile as per above.
  • we update local state with the reconciled scene we get when saving to firebase
• decoupled broadcasting from saving to firebase for better clarity

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployments, click below or on the icon next to each commit.

excalidraw – ./

🔍 Inspect: https://vercel.com/excalidraw/excalidraw/CKFXdTo4er2pyhE5nxuxvHvQMMx6
✅ Preview: https://excalidraw-git-collabreconciliation-excalidraw.vercel.app

excalidraw-package-example – ./src/packages/excalidraw

🔍 Inspect: https://vercel.com/excalidraw/excalidraw-package-example/9Ep31P4jY2gLQY4xANadngRDNDjd
✅ Preview: https://excalidraw-package-example-git-collabreconciliation-excalidraw.vercel.app