Bump watch_it from 1.7.0 to 2.0.0

[dependabot]

Bumps watch_it from 1.7.0 to 2.0.0.

Changelog

Sourced from watch_it's changelog.

2.0.0 - Performance optimizations and post-frame callbacks

Breaking Changes

• BREAKING: Replaced dependency functional_listener ^4.0.0 with listen_it ^5.1.0. This is a breaking change as functional_listener has been renamed and restructured into listen_it. If you use functional_listener operators in your code, update your imports from package:functional_listener/functional_listener.dart to package:listen_it/listen_it.dart.
• BREAKING: watchValue() and registerHandler() now default to allowObservableChange: false for better performance and memory leak prevention. This means the selector function is only called once on first build. If you need to dynamically switch observables (e.g., condition ? obsA : obsB), set allowObservableChange: true. This prevents common memory leaks from inline chain creation like watchValue((m) => m.source.map(...)).

New Features

• Added callAfterFirstBuild() function that executes a callback once after the first frame has been rendered. This is useful for operations that require the widget tree to be fully built and laid out, such as showing dialogs, accessing widget dimensions, scrolling to positions, or starting animations that depend on final widget sizes. This replaces the common pattern of using WidgetsBinding.instance.addPostFrameCallback in initState().
• Added callAfterEveryBuild() function that executes a callback after every frame has been rendered. This is useful for operations that need to run after each rebuild, such as updating scroll positions, repositioning overlays, or performing measurements. The callback includes a cancel() function to stop future invocations when needed.

Performance Improvements

• watchValue() and registerHandler() now have zero overhead on rebuilds with default settings - selectors are only called once instead of on every build
• Added helpful StateError messages when observables change unexpectedly with allowObservableChange: false, guiding users to the correct fix

Bug Fixes

• Fixed createOnceAsync test isolation issue by properly resetting testCompleter in setUp
• Internal refactoring: Renamed parameters for better clarity (target → parentOrListenable, etc.)

Commits

• See full diff in compare view

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