Add package:assets

[mosuem]

Adding (very experimental) package:assets.

The basic idea: Users can use the hook helpers to add assets (which sends them to this package for linking by default), StringAsset/ByteAsset to load them, and they are treeshaken in the link hook. Alternatively, asset_internal can be used to implement their own wrappers for custom asset types.

Open to a discussion about whether this should live here or in the Dart SDK (https://dart-review.googlesource.com/c/sdk/+/412920). @mkustermann @devoncarew ?

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[github-actions]

PR Health

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
assets	Breaking	0.0.2	0.1.0	0.1.0	✔️

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

Coverage ⚠️

File	Coverage
pkgs/assets/example/assets_example.dart	💔 Not covered
pkgs/assets/hook/link.dart	💔 Not covered
pkgs/assets/lib/assets.dart	💔 Not covered
pkgs/assets/lib/assets_hook.dart	💔 Not covered
pkgs/assets/lib/assets_internal.dart	💔 Not covered
pkgs/assets/lib/src/assets.dart	💔 Not covered
pkgs/assets/lib/src/assets_internal.dart	💔 Not covered
pkgs/assets/lib/src/hook/assets_build.dart	💔 Not covered
pkgs/assets/lib/src/hook/assets_link.dart	💔 Not covered

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API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols

License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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