feat(signals): add prepend entity updaters

[dimavasylyna]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

The addEntity function in @ngrx/signals currently appends new entities to the end of the entities array by default. There is no way to control the insertion order, limiting flexibility in scenarios where entities need to be added at the beginning (e.g., for "most recent first" displays).

Closes #4723

What is the new behavior?

This PR adds new prependEntity and prependEntities entity updaters for adding entities to the beginning of the collection.

Example

patchState(store, prependEntity(user1));
// Result: entities = [user1, ...existingEntities]

patchState(store, prependEntites([user1, user2]));
// Result: entities = [user1, user2, ...existingEntities]

Does this PR introduce a breaking change?

[ ] Yes
[x] No

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[markostanimirovic]

Hi @dimavasylyna,

Can you open a new GitHub issue (feature request) for this feature? Based on the community feedback, we'll decide if this feature should land and how it should be designed. You can find more info on this topic in our contribution guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#submitting-new-features

[dimavasylyna]

Hi @markostanimirovic,
Thanks for the feedback! I’ve opened a new feature request as an RFC issue per the contribution guidelines. You can find it here: RFC: Add prepend option to addEntity in @ngrx/signals/entities #4723. Looking forward to community input on this!

[markostanimirovic]

Great work @dimavasylyna! I left a few suggestions:

[markostanimirovic]

LGTM 👌

[timdeschryver]

Some small nits