feat: widen support to Angular 20-22

[JasonWeinzierl]

Description

• Widen the peer dependency range from Angular 21 to Angular 20-22, to support the Angular versions under active support (https://angular.dev/reference/releases#actively-supported-versions).
  • Added a peer dependency CI script to ensure compatibility works.
    • There are alternative ways to accomplish this. I considered: (1) using ng new to bootstrap fresh projects. Seemed to be more than we need, and probably slower. (2) in-place modifying the package.json dependencies to 20, 21, and 22. Less isolated than the temporary directory approach and risks mutating the library so the test isn't accurate.
  • Downgrade the repository (and demo site) to Angular 20 because per Angular documentation (https://angular.dev/tools/libraries/creating-libraries#ensuring-library-version-compatibility), you should build libraries with the lowest supported Angular version.
• Replaced .nvmrc with .node-version, thanks for the recommendation in Feature/angular v22 support #7 .
• Added platform-browser to the peer dependencies to fix pnpm support and avoid a hidden dependency.
• Did demo app simplifications per Feature/angular v22 support #7 .

Related issues

Fixes #6

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that changes the public API)
• Documentation only
• Refactor, test, or chore (no user-facing change)

Breaking changes

None

This should not be a breaking change since we're maintaining support for Angular 21.

Test plan

• npm run build
• npm test
• npm run lint
• Verified in the demo app (if applicable)

Checklist

• Issue discussed or bug clearly described (link issue when applicable)
• Tests added or updated for behavioral changes
• Documentation updated (README, JSDoc, migration notes as needed)
• Public API changes documented; breaking changes called out
• CHANGELOG updated (if the repository maintains one and the change is user-facing)
• Commit messages follow Conventional Commits
• I agree to follow the OpenNG Foundation Code of Conduct

Additional context

[Copilot]

Pull request overview

Expands Angular support to versions 20–22, updates the project baseline to Angular 20, and migrates tests to Vitest.

Changes:

• Widens Angular peer dependencies and adds compatibility CI.
• Updates dependencies, documentation, and Node version configuration.
• Replaces Karma/Jasmine testing with Vitest.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Summary
tsconfig.spec.json	Configures Vitest globals.
src/app/toasts.spec.ts	Migrates tests to Vitest APIs.
scripts/test-peer-compatibility.mjs	Adds Angular-version compatibility testing.
README.md	Documents Angular 20–22 support.
projects/ngx-toastr/package.json	Widens Angular peer dependencies.
package.json	Updates Angular and test tooling dependencies.
karma.conf.js	Removes obsolete Karma configuration.
angular.json	Configures the Vitest test target; critical issue: invalid Karma-style coverage option names will prevent ng test from running.
.nvmrc	Replaced by .node-version.
.node-version	Defines the Node.js version.
.github/workflows/publish.yml	Uses .node-version.
.github/workflows/pr-title.yml	Uses .node-version.
.github/workflows/ci.yml	Adds Angular compatibility testing.

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[Copilot]

Pull request overview

Copilot reviewed 13 out of 14 changed files in this pull request and generated no new comments.

[majora2007]

Any chance we can get this merged? This is the last dependency blocking my update to Angular 22.