fix: localize English UI strings

frontend/src/views/user/CustomPageView.vue

@@ -35,7 +35,7 @@
             class="toc-sidebar"
           >
             <div class="toc-header">
-              <span class="toc-title">目录</span>
+              <span class="toc-title">{{ t('customPage.tableOfContents') }}</span>
               <button class="toc-close-btn" @click="tocVisible = false">
                 <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M15 18l-6-6 6-6"/></svg>
               </button>
@@ -64,7 +64,7 @@
             @click="tocVisible = true"
           >
             <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M3 12h18M3 6h18M3 18h18"/></svg>
-            <span class="ml-1 text-xs">目录</span>
+            <span class="ml-1 text-xs">{{ t('customPage.tableOfContents') }}</span>
           </button>
 
           <!-- Content -->
@@ -317,16 +317,16 @@ function injectCopyButtons() {
     if (pre.querySelector('.copy-btn')) return
     const btn = document.createElement('button')
     btn.className = 'copy-btn'
-    btn.textContent = '复制'
+    btn.textContent = t('customPage.copyCode')
     btn.addEventListener('click', async () => {
       const code = pre.querySelector('code')?.textContent ?? pre.textContent ?? ''
       try {
         await navigator.clipboard.writeText(code)
-        btn.textContent = '已复制 ✓'
-        setTimeout(() => { btn.textContent = '复制' }, 2000)
+        btn.textContent = t('customPage.copiedCode')
+        setTimeout(() => { btn.textContent = t('customPage.copyCode') }, 2000)
       } catch {
-        btn.textContent = '失败'
-        setTimeout(() => { btn.textContent = '复制' }, 2000)
+        btn.textContent = t('customPage.copyCodeFailed')
+        setTimeout(() => { btn.textContent = t('customPage.copyCode') }, 2000)
       }
     })
     pre.style.position = 'relative'