fix(webui): destructure non-reactive steps from setup store directly

`steps` is a plain array in the store, not a ref. Using `storeToRefs`
returned undefined, causing "Cannot read properties of undefined
(reading 'length')" at runtime.

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

webui/src/pages/setup.vue

@@ -4,7 +4,8 @@ definePage({
 });
 
 const setupStore = useSetupStore();
-const { currentStep, currentStepIndex, steps } = storeToRefs(setupStore);
+const { currentStep, currentStepIndex } = storeToRefs(setupStore);
+const { steps } = setupStore;
 </script>
 
 <template>