feat: add react native web support

[Robert27]

Added support for react native web by adapting the dispatcher behavior from aptabase-js.

• Created two new dispatcher classes to handle dispatching for each platform.
• Updated various files to handle the new platform
• Updated a few dependencies
• Added and updated the vitest tests.

Resolves #12

[ivnbogdan]

@Robert27 thank you for your contribution.

Can you please highlight in a comment here the differences in implementation between the two and the reasoning for explicit support for React Native Web?

[Robert27]

React Native Web has become increasingly popular, especially since Expo Web. The Bluesky web app, for example, is written with React Native Web. Specifically, I need this feature for my team, and I read the request in the discord. However, this SDK does not yet support the web platform.

Implementing it turned out to be a bit more complicated, as different philosophies were chosen between native and web.
I analyzed the other SDKs and used a comment from the founder in Discord. So web sends the events immediately, because the browser can be closed at any time, but native on the other hand batched to another endpoint, which also has no CORS restrictions.
Consequently, I had to create two dispatchers, one for web to the single event endpoint without user agent, so that CORS works, and the other one is the unmodified native dispatcher

[beshkin]

I can absolutely relate on this PR.
@Robert27 great job. I checked the implementation and looks like exactly what we need

[Robert27]

I have added all the desired changes and the web functionality is now opt-in. I was also able to solve all issues with the tests and also added new ones. In addition I also updated the documentation in the readme accordingly.

My team is already using my fork in production and everything works without any problems.