Initial commit of package:js_interop 0.1.0-beta (#476)

Making a breaking change to avoid breaking any existing users of
package:js_interop. Also modifies the monorepo's README to detail
the packages within rather than being a symlink to web's README.

Author: srujzs

README.md

@@ -0,0 +1,9 @@
+<!-- TODO(srujzs): Add links to CI once we have a badge that doesn't say "package:web" and is more generic. -->
+
+## Packages
+
+| Package                         | Description                                                                                                                                                              | Version                                                                                            |
+| ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------- |
+| [web](web/)                     | Lightweight browser API bindings built around [JS interop](https://dart.dev/interop/js-interop).                                                                         | [![pub package](https://img.shields.io/pub/v/web.svg)](https://pub.dev/packages/web)               |
+| [js_interop](js_interop/)       | Utility functions and types for [`dart:js_interop`](https://api.dart.dev/dart-js_interop/) and [`dart:js_interop_unsafe`](https://api.dart.dev/dart-js_interop_unsafe/). | [![pub package](https://img.shields.io/pub/v/js_interop.svg)](https://pub.dev/packages/js_interop) |
+| [web_generator](web_generator/) | Tools to generate Dart interfaces from TypeScript declaration files and Web IDL definitions.                                                                             | N/A                                                                                                |

README.md

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+## 0.1.0-beta
+
+- Initial release.

js_interop/CHANGELOG.md

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+Copyright 2025, the Dart project authors.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google LLC nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

js_interop/LICENSE

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+[![pub package](https://img.shields.io/pub/v/js_interop.svg)](https://pub.dev/packages/js_interop)
+[![package publisher](https://img.shields.io/pub/publisher/js_interop.svg)](https://pub.dev/packages/js_interop/publisher)
+
+Utility functions and types for [`dart:js_interop`](https://api.dart.dev/dart-js_interop/) and [`dart:js_interop_unsafe`](https://api.dart.dev/dart-js_interop_unsafe/).

js_interop/README.md

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+name: js_interop
+version: 0.1.0-beta
+description: Utility APIs for dart:js_interop and dart:js_interop_unsafe.
+repository: https://github.com/dart-lang/web
+
+environment:
+  sdk: ^3.9.0

js_interop/pubspec.yaml

@@ -1,6 +1,6 @@
 ## What's this?
 
-This package contains tools to generate Dart interfaces from TypeScript Declaration code and Web IDL definitions.
+Tools to generate Dart interfaces from TypeScript declaration files and Web IDL definitions.
 
 This package is used to generate
 [`web`](https://github.com/dart-lang/web/tree/main/web) from Web IDL definitions