feat(ui): update SignInForm default authentication error message

[franzheidl]

This PR updates the default authentication message on the SignInForm to "Unable to authenticate the provided credentials.", and adds a story showing the default error on the form when the error prop is passed as true.

Screenshots

Testing Instructions

1. pnpm i
2. pnpm run test SignInForm

Checklist

• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have made corresponding changes to the documentation (if applicable).
• My changes generate no new warnings or errors.
• I have created a changeset for my changes.

PR Manifesto

Review the PR Manifesto for best practises.

[changeset-bot]

🦋 Changeset detected

Latest commit: 17b5f82

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
@cloudoperators/juno-ui-components	Patch
@cloudoperators/juno-app-carbon	Patch
@cloudoperators/juno-app-doop	Patch
@cloudoperators/juno-app-example	Patch
@cloudoperators/juno-app-greenhouse	Patch
@cloudoperators/juno-app-heureka	Patch
@cloudoperators/juno-app-supernova	Patch
@cloudoperators/juno-app-template	Patch
@cloudoperators/juno-messages-provider	Patch

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[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-07-15 09:32 UTC

[Copilot]

Pull request overview

Updates the SignInForm component in @cloudoperators/juno-ui-components to use a new default authentication error message and documents/demonstrates this behavior via Storybook and tests.

Changes:

• Updated the default error={true} message to “Unable to authenticate the provided credentials.”
• Added a Storybook story that renders the form with the default error state.
• Updated unit tests and added a changeset for the patch release.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
packages/ui-components/src/components/SignInForm/SignInForm.component.tsx	Updates the default error message string and its prop documentation.
packages/ui-components/src/components/SignInForm/SignInForm.test.tsx	Updates assertions to match the new default error message.
packages/ui-components/src/components/SignInForm/SignInForm.stories.tsx	Adds a WithError story to showcase the default error state.
.changeset/shiny-clowns-divide.md	Adds a patch changeset for the UI components package.