Accessible Elevation

[TeyaVes]

related to: https://github.com/telerik/kendo-themes-private/issues/413

In this PR:

• Added k-elevation-accessible() mixin

• Implements dual-mode elevation system:

  • Light themes: Uses traditional box-shadow elevation
  • Dark themes: Uses color-mix() to lighten backgrounds progressively

• Added elevation background step map ($kendo-elevation-bg) with 9 levels (2%-32%)

• Updated action-sheet components across all themes to use the new accessible elevation

• Added is-dark-theme: true variable to dark theme swatches

---

Things to consider:

• We can decide to keep only the mixin instead of the function with the accessible attribute set to false, which would fallback to the current implementation
• Names are up to consideration
• The $default-elevation-bg-step map values should be changed as well
• Currently, the mixin lightens the background color, but we should check if this would be sufficient

[github-actions]

Packages Report

	core	default	classic	bootstrap	material	fluent	utils	html
Size	29.51 KB (1.1%🔼)	769.67 KB (0.0%🔼)	768.31 KB (0.0%🔼)	783.23 KB (0.0%🔼)	916.39 KB (0.0%🔼)	1181.87 KB (0.0%🔼)	625.19 KB (0.0%)	77.78 MB (0.0%)
Gzip Size	4.90 KB (1.0%🔼)	99.45 KB (0.1%🔼)	99.68 KB (0.0%🔼)	101.42 KB (0.0%🔼)	112.38 KB (0.0%🔼)	136.85 KB (0.0%🔼)	52.16 KB (0.0%)	15.95 MB (0.0%)
Compile Time	0.8 s (0.0%)	3.2 s (0.0%)	3.1 s (0.0%)	3.1 s (0.0%)	2.9 s (0.0%)	3.7 s (0.0%)	2.7 s (0.0%)	8.2 s (0.0%)