feat(theme): export themes constant

[metonym]

Closes #939

Export the themes constant from the Theme component to provide programmatic access to all available Carbon theme keys and their human-readable labels.

Changes

The themes constant is now exported as a module-level constant from Theme.svelte, making it available for import alongside the Theme component. This constant was previously only available internally within the Theme component.

import { themes } from "carbon-components-svelte/src/Theme/Theme.svelte";

// Access all theme keys
const themeKeys = Object.keys(themes);

// Build custom UI with correct labels
Object.entries(themes).forEach(([key, label]) => {
  // Use key and label to build theme options
});

[metonym]

Released in v0.94.0