fix: slider in react and update react deps

[christopherGdynia]

Description

This PR adds React 19 support to @telekom/scale-components-react and fixes a runtime crash in the scale-slider component that surfaced when running under the React (custom elements) build.

Changes

1. React 19 type support (packages/components-react/package.json)

• Widened the @types/react-dom peer dependency range from ^18.3.1 to ^18.3.1 || ^19.0.0, so consumers on either React 18 or React 19 satisfy the peer requirement.
• Marked @types/react-dom as optional via peerDependenciesMeta (types are only needed at build time, not by every consumer).

2. Slider crash fix (packages/components/src/components/slider/slider.tsx)

• Renamed the internal state key offsetLeft → trackOffsetLeft (and its range variants trackOffsetLeftFrom / trackOffsetLeftTo).
• The component previously wrote to this.offsetLeft, which collides with the read-only native HTMLElement.offsetLeft getter. In the React / custom-elements build the component class extends HTMLElement, so this assignment threw at runtime.

Bug fixed

Cannot set property offsetLeft of [object HTMLElement] which has only a getter

Root cause: The slider stored the track's left offset on this.offsetLeft. This worked in the lazy build (where the instance is not an HTMLElement) but crashed in the React/custom-elements build, where offsetLeft is a read-only DOM property. This is a library-side issue, not a consumer implementation problem — the React 19 upgrade only made it visible.

Impact

• No public API changes; the renamed key is internal only.
• Fixes drag interaction for scale-slider (single and range) in React.
• Enables React 19 consumers to install without peer dependency conflicts.

Testing

• Verified slider drag works in the React example app
• Verified install with React 18
• Verified install with React 19
• Rebuilt @telekom/scale-components and @telekom/scale-components-react

[Copilot]

Pull request overview

This PR updates the React wrapper package to accept React 19 type definitions and fixes a runtime crash in scale-slider caused by writing to the read-only native HTMLElement.offsetLeft property in the custom-elements/React build.

Changes:

• Renames the slider’s internal offsetLeft state key to trackOffsetLeft to avoid clashing with HTMLElement.offsetLeft.
• Widens @types/react-dom peer dependency range to include React 19 and marks it optional via peerDependenciesMeta.

Reviewed changes

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

File	Description
packages/components/src/components/slider/slider.tsx	Avoids runtime crash by renaming the internal offset key away from offsetLeft.
packages/components-react/package.json	Expands peer type compatibility to React 19 and marks @types/react-dom as optional.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.