fix: Launch app for Web

[riscait]

🔗 Related Issues

• closes White screen when launching app on Chrome #376

🙌 What's Done

• Fix UserDevice (Use sealed class)
• dart:isolate is note used on the web

✍️ What's Not Done

🖼️ Image Differences

📝 Additional Notes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 23.75%. Comparing base (c5160cd) to head (70739e0).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #409   +/-   ##
=======================================
  Coverage   23.75%   23.75%           
=======================================
  Files          13       13           
  Lines         160      160           
=======================================
  Hits           38       38           
  Misses        122      122           

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[naipaka]