Add Web Platform Support to clerk_auth Dart Library

[Turskyi]

Use case

While clerk_auth is marketed as platform-agnostic, it currently lacks Web platform support. The common stance is that “we already support web via JavaScript”, but that misses a major real-world use case for Flutter developers.

Many Flutter projects are not just mobile - developers often embed Flutter modules into existing web apps via <iframe> to reuse complex features already implemented in Flutter, instead of rebuilding them in JavaScript. This pattern is common for features that:
• Have heavy business logic or complex UI already written in Flutter.
• Need to be embedded in an existing non-Flutter web app without reimplementation.

For example, I may have a Flutter-built custom Excel file uploader/parser that sends structured data to the backend. It works perfectly on mobile. Without Web support in clerk_auth, I cannot embed this exact feature in my web app via an iframe - I would need to reimplement it entirely in JavaScript, which defeats the purpose of using Flutter for cross-platform code reuse.

By lacking Web support, clerk_auth forces unnecessary rewrites and pushes developers toward alternative auth solutions that work across mobile and web in Flutter projects.

Proposal

Add official Web platform support for clerk_auth.
• Ensure authentication APIs work when compiled to Flutter Web.
• Keep it platform-agnostic as advertised, so it can run in iOS, Android, macOS, Windows, Linux, and Web without separate code paths.
• This allows developers to reuse Flutter modules across mobile and web, including embedding them in existing JavaScript apps via iframe.

[benherronscope]

I agree completely with this ticket, we are using Flutter for cross platform including web, and this is a deal breaker for us using Clerk for the authentication.