Fix Home Assistant 2025.5 theming compatibility

[alxDisplayr]

Description

This PR fixes the theming compatibility issue with Home Assistant 2025.5 reported in #246.

Problem

Home Assistant 2025.5 introduced breaking changes to theming and typography, specifically removing the deprecated --paper-item-icon-color CSS variable. This was causing icons in the slider-button-card to display with wrong colors (white icons, black action buttons) instead of theme-appropriate colors.

Solution

Replaced all instances of the deprecated --paper-item-icon-color variable with the new --state-icon-color variable as specified in the Home Assistant 2025.5 breaking changes documentation.

Changes Made

• ✅ Updated src/slider-button-card.ts to use --state-icon-color instead of --paper-item-icon-color
• ✅ Rebuilt the distribution file dist/slider-button-card.js with the updated changes
• ✅ Maintained backward compatibility with fallback values
• ✅ Updated both active styles and commented fallback styles for consistency

Testing

• ✅ Project builds successfully without errors
• ✅ All instances of deprecated variable have been replaced
• ✅ Distribution file has been updated with the changes

Fixes

Fixes #246

Compatibility

This change ensures compatibility with:

• ✅ Home Assistant 2025.5 and later
• ✅ Earlier Home Assistant versions (through fallback values)

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Note: This is a critical fix for users running Home Assistant 2025.5+ who are experiencing icon theming issues.

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Pull Request opened by Augment Code with guidance from the PR author