Enable onAnimationModalInEnd callback

[pichfl]

Closes #637

[pichfl]

@nickschot and I went on a wild chase Even though this "fixes" the issue, it most likely does so by covering up the actual problem while also introducing a lot of moving parts. My initial assumption that animationend might not trigger when a user enables prefers-reduce-motion is wrong, all tested browsers still trigger the event even if the animation time is reduced to 0s. If there is a "valid" animation, it will trigger the event.

Quoting MDN (emphasis by me):

The animationend event is fired when a CSS Animation has completed. If the animation aborts before reaching completion, such as if the element is removed from the DOM or the animation is removed from the element, the animationend event is not fired.

We want to make sure, that janking the model component still triggers all necessary parts, but we shouldn't do so by introducing timers. Instead #686 is most likely one of the problems behind #665

I'm keeping this PR open for reference until #665 is resolved.

[marcin-wicha]

Is anything blocking this currently? All of the referenced issues have been merged/closed.

[pichfl]

I've rebased and refactored to match the latest iteration, hoping to get this in with the next release.

[Copilot]

Pull Request Overview

Enables and documents a new onAnimationModalInEnd callback for opening animations, updates the modal component to invoke it, and adds an integration test to verify its invocation.

• Introduce onAnimationModalInEnd option in modal API, component, and docs
• Update EpmModal to expose and invoke the new callback
• Add an integration test and adjust helpers/mocks to support animation callbacks

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/test-app/tests/integration/components/modal-test.js	Add a test for onAnimationModalInEnd and onAnimationModalOutEnd callbacks
packages/test-app/tests/helpers/mocks.js	Extend the default mock modal to support a click-to-close action
packages/test-app/tests/application/basics-test.js	Remove obsolete sinon-based animation-start test
packages/ember-promise-modals/src/components/epm-modal.js	Add an options getter and invoke the new onAnimationModalInEnd callback
packages/ember-promise-modals/src/components/epm-modal.hbs	Update class binding to use options.className
packages/ember-promise-modals/README.md	Document the new onAnimationModalInEnd hook
README.md	Document the new onAnimationModalInEnd hook in the root README

[Copilot]

[nitpick] The click import is never used in this test. Remove it or add a click step to exercise the mock’s close button.

[Copilot]

This calls the "in end" callback for all animations, including the closing animation. It should only fire when the modal’s opening animation ends, and onAnimationModalOutEnd should be invoked for closing animations.

Suggested change

	this.options.onAnimationModalInEnd?.(animationName);
	if (isOutAnimation) {
	this.options.onAnimationModalOutEnd?.(animationName);
	} else {
	this.options.onAnimationModalInEnd?.(animationName);
	}

[Copilot]

[nitpick] An animationend listener is added but never removed. Consider cleaning it up (e.g., in a willDestroy hook) to prevent memory leaks when the component is destroyed.