fix(svelte): variantState should not be modified by component internal state

[sun0day]

Description

fix #264

Since Vue.watch will use Proxy to wrapper svelte component state value, once component state value changed, the global variantState changed in the same time which will make applyState useless and the watch callback not be triggered.

We can use histoire/shared.clone to cut the relation between variantState and component internal state.

Additional context

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• Bug fix
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[sun0day]

@Akryum Can you take the time to review this pr at your convenience？