fix(frontend): 修复账号管理页面 API Key 类型的提示文案错误

- 添加 OpenAI/Gemini 平台的 baseUrlHint 和 apiKeyHint 国际化文案
- 修改 CreateAccountModal 和 EditAccountModal 根据平台显示正确提示
- 将重复的平台判断逻辑抽取为 computed 属性，优化代码结构

frontend/src/components/account/CreateAccountModal.vue

@@ -530,7 +530,7 @@
                   : 'https://api.anthropic.com'
             "
           />
-          <p class="input-hint">{{ t('admin.accounts.baseUrlHint') }}</p>
+          <p class="input-hint">{{ baseUrlHint }}</p>
         </div>
         <div>
           <label class="input-label">{{ t('admin.accounts.apiKeyRequired') }}</label>
@@ -547,13 +547,7 @@
                   : 'sk-ant-...'
             "
           />
-          <p class="input-hint">
-            {{
-              form.platform === 'gemini'
-                ? t('admin.accounts.gemini.apiKeyHint')
-                : t('admin.accounts.apiKeyHint')
-            }}
-          </p>
+          <p class="input-hint">{{ apiKeyHint }}</p>
         </div>
 
         <!-- Model Restriction Section (不适用于 Gemini) -->
@@ -1115,6 +1109,19 @@ const oauthStepTitle = computed(() => {
   return t('admin.accounts.oauth.title')
 })
 
+// Platform-specific hints for API Key type
+const baseUrlHint = computed(() => {
+  if (form.platform === 'openai') return t('admin.accounts.openai.baseUrlHint')
+  if (form.platform === 'gemini') return t('admin.accounts.gemini.baseUrlHint')
+  return t('admin.accounts.baseUrlHint')
+})
+
+const apiKeyHint = computed(() => {
+  if (form.platform === 'openai') return t('admin.accounts.openai.apiKeyHint')
+  if (form.platform === 'gemini') return t('admin.accounts.gemini.apiKeyHint')
+  return t('admin.accounts.apiKeyHint')
+})
+
 interface Props {
   show: boolean
   proxies: Proxy[]

frontend/src/components/account/EditAccountModal.vue

@@ -32,7 +32,7 @@
                   : 'https://api.anthropic.com'
             "
           />
-          <p class="input-hint">{{ t('admin.accounts.baseUrlHint') }}</p>
+          <p class="input-hint">{{ baseUrlHint }}</p>
         </div>
         <div>
           <label class="input-label">{{ t('admin.accounts.apiKey') }}</label>
@@ -536,6 +536,14 @@ const emit = defineEmits<{
 const { t } = useI18n()
 const appStore = useAppStore()
 
+// Platform-specific hint for Base URL
+const baseUrlHint = computed(() => {
+  if (!props.account) return t('admin.accounts.baseUrlHint')
+  if (props.account.platform === 'openai') return t('admin.accounts.openai.baseUrlHint')
+  if (props.account.platform === 'gemini') return t('admin.accounts.gemini.baseUrlHint')
+  return t('admin.accounts.baseUrlHint')
+})
+
 // Model mapping type
 interface ModelMapping {
   from: string