Flutter Web improvements

We are pleased to announce release 1.6.0 of the PowerSync Dart SDK, which includes many improvements to our Flutter Web support.

Enhancements in this version:

1. Use of the new sqlite3_web package from Simon Binder, the maintainer for Dart’s SQLite3 and Drift packages:

   1. This gives us support for DB connections being shared between multiple tabs and it also seems to result in a much more responsive Flutter Web application.

2. More robust multiple tab support

   1. We also implemented navigator locks which are shared between tabs, making multiple tab support more reliable (in the future we'll implement shared sync coordination between tabs).

3. Web support in sqlite_async.dart:

   1. This allows using the Drift ORM helper package in Flutter Web.

Other changes for improved maintainability and support going forward:

1. Flutter Web support is now available in the main powersync package (no longer the separate -alpha branch)

2. sqlite_async monorepo (now includes the drift_sqlite_async package preventing issues like outdated dependencies)