feat(i18n): add language switcher component to navigation

frontend/src/components/LanguageSwitcher.vue

@@ -0,0 +1,153 @@
+<template>
+  <div class="language-switcher" :class="{ dark: dark }" ref="switcherRef">
+    <button class="switcher-trigger" @click="toggleDropdown">
+      {{ currentLabel }}
+      <span class="caret">{{ open ? '▲' : '▼' }}</span>
+    </button>
+    <ul v-if="open" class="switcher-dropdown">
+      <li
+        v-for="loc in availableLocales"
+        :key="loc.key"
+        class="switcher-option"
+        :class="{ active: loc.key === locale }"
+        @click="switchLocale(loc.key)"
+      >
+        {{ loc.label }}
+      </li>
+    </ul>
+  </div>
+</template>
+
+<script setup>
+import { ref, computed, onMounted, onUnmounted } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { availableLocales } from '@/i18n/index.js'
+
+const props = defineProps({
+  dark: {
+    type: Boolean,
+    default: false
+  }
+})
+
+const { locale } = useI18n()
+const open = ref(false)
+const switcherRef = ref(null)
+
+const currentLabel = computed(() => {
+  const found = availableLocales.find(l => l.key === locale.value)
+  return found ? found.label : locale.value
+})
+
+const toggleDropdown = () => {
+  open.value = !open.value
+}
+
+const switchLocale = (key) => {
+  locale.value = key
+  localStorage.setItem('locale', key)
+  document.documentElement.lang = key
+  open.value = false
+}
+
+const onClickOutside = (e) => {
+  if (switcherRef.value && !switcherRef.value.contains(e.target)) {
+    open.value = false
+  }
+}
+
+onMounted(() => {
+  document.addEventListener('click', onClickOutside)
+  document.documentElement.lang = locale.value
+})
+
+onUnmounted(() => {
+  document.removeEventListener('click', onClickOutside)
+})
+</script>
+
+<style scoped>
+.language-switcher {
+  position: relative;
+  display: inline-block;
+  font-family: 'JetBrains Mono', monospace;
+}
+
+/* Light theme (default - for white header backgrounds) */
+.switcher-trigger {
+  background: transparent;
+  color: #333;
+  border: 1px solid #CCC;
+  padding: 4px 12px;
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.8rem;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  transition: border-color 0.2s, opacity 0.2s;
+}
+
+.switcher-trigger:hover {
+  border-color: #999;
+}
+
+.caret {
+  font-size: 0.6rem;
+}
+
+.switcher-dropdown {
+  position: absolute;
+  top: 100%;
+  right: 0;
+  margin-top: 4px;
+  background: #FFFFFF;
+  border: 1px solid #DDD;
+  list-style: none;
+  padding: 4px 0;
+  min-width: 100%;
+  z-index: 1000;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+}
+
+.switcher-option {
+  padding: 6px 12px;
+  font-size: 0.8rem;
+  color: #333;
+  cursor: pointer;
+  white-space: nowrap;
+  transition: background 0.15s;
+}
+
+.switcher-option:hover {
+  background: #F0F0F0;
+}
+
+.switcher-option.active {
+  color: var(--orange, #FF4500);
+}
+
+/* Dark theme (for dark navbar backgrounds) */
+.dark .switcher-trigger {
+  color: var(--white, #FFFFFF);
+  border-color: rgba(255, 255, 255, 0.3);
+}
+
+.dark .switcher-trigger:hover {
+  border-color: rgba(255, 255, 255, 0.6);
+}
+
+.dark .switcher-dropdown {
+  background: var(--black, #000000);
+  border-color: rgba(255, 255, 255, 0.2);
+  box-shadow: none;
+}
+
+.dark .switcher-option {
+  color: var(--white, #FFFFFF);
+}
+
+.dark .switcher-option:hover {
+  background: rgba(255, 255, 255, 0.1);
+}
+</style>

frontend/src/views/Home.vue

@@ -4,6 +4,7 @@
     <nav class="navbar">
       <div class="nav-brand">MIROFISH</div>
       <div class="nav-links">
+        <LanguageSwitcher dark />
         <a href="https://github.com/666ghj/MiroFish" target="_blank" class="github-link">
           访问我们的Github主页 <span class="arrow">↗</span>
         </a>
@@ -210,6 +211,7 @@
 import { ref, computed } from 'vue'
 import { useRouter } from 'vue-router'
 import HistoryDatabase from '../components/HistoryDatabase.vue'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const router = useRouter()
 
@@ -351,6 +353,7 @@ const startSimulation = () => {
 .nav-links {
   display: flex;
   align-items: center;
+  gap: 16px;
 }
 
 .github-link {

frontend/src/views/InteractionView.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 5/5</span>
           <span class="step-name">深度互动</span>
@@ -69,6 +71,7 @@ import Step5Interaction from '../components/Step5Interaction.vue'
 import { getProject, getGraphData } from '../api/graph'
 import { getSimulation } from '../api/simulation'
 import { getReport } from '../api/report'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const route = useRoute()
 const router = useRouter()

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()

frontend/src/views/ReportView.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 4/5</span>
           <span class="step-name">报告生成</span>
@@ -69,6 +71,7 @@ import Step4Report from '../components/Step4Report.vue'
 import { getProject, getGraphData } from '../api/graph'
 import { getSimulation } from '../api/simulation'
 import { getReport } from '../api/report'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const route = useRoute()
 const router = useRouter()

frontend/src/views/SimulationRunView.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 3/5</span>
           <span class="step-name">开始模拟</span>
@@ -73,6 +75,7 @@ import GraphPanel from '../components/GraphPanel.vue'
 import Step3Simulation from '../components/Step3Simulation.vue'
 import { getProject, getGraphData } from '../api/graph'
 import { getSimulation, getSimulationConfig, stopSimulation, closeSimulationEnv, getEnvStatus } from '../api/simulation'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const route = useRoute()
 const router = useRouter()

frontend/src/views/SimulationView.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 2/5</span>
           <span class="step-name">环境搭建</span>
@@ -70,6 +72,7 @@ import GraphPanel from '../components/GraphPanel.vue'
 import Step2EnvSetup from '../components/Step2EnvSetup.vue'
 import { getProject, getGraphData } from '../api/graph'
 import { getSimulation, stopSimulation, getEnvStatus, closeSimulationEnv } from '../api/simulation'
+import LanguageSwitcher from '../components/LanguageSwitcher.vue'
 
 const route = useRoute()
 const router = useRouter()