Use semantic colour names

[SjaakSchilperoort]

User story

As a component library developer,
I want colour tokens to have semantic names that map to a shared palette,
So that components express intent rather than raw values, enabling light and dark themes to be defined by remapping the same semantic tokens to different palette colours.

Acceptance criteria:

• A private palette object holds all raw hex color values
• The Color interface uses semantic names only (no scale-based names like grey800 or primary500)
• lightColor object implements the Color interface by mapping semantic names to palette values
• The library exports a lightTheme, built with the corresponding color map
• All components and text styles in the library reference color by semantic names only
• The Color interface retains the old property names marked @deprecated (so app color objects still satisfy the type and compile with warnings)
• The deprecated properties are removed in a follow-up story, once all apps have migrated their color objects