feat(i18n): add language switcher component to navigation

frontend/src/views/MainView.vue

@@ -21,6 +21,8 @@
       </div>
 
       <div class="header-right">
+        <LanguageSwitcher />
+        <div class="step-divider"></div>
         <div class="workflow-step">
           <span class="step-num">Step {{ currentStep }}/5</span>
           <span class="step-name">{{ stepNames[currentStep - 1] }}</span>
@@ -82,6 +84,7 @@ import Step1GraphBuild from '../components/Step1GraphBuild.vue'
 import Step2EnvSetup from '../components/Step2EnvSetup.vue'
 import { generateOntology, getProject, buildGraph, getTaskStatus, getGraphData } from '../api/graph'
 import { getPendingUpload, clearPendingUpload } from '../store/pendingUpload'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const route = useRoute()
 const router = useRouter()