refactor(frontend): 清理OpsDashboardHeader中的i18n翻译

将技术术语的i18n翻译键替换为硬编码文本：
- ms (P99) - 毫秒和百分位数标识
- TTFT - Time To First Token缩写

这些是通用技术术语，不需要国际化。

frontend/src/views/admin/ops/components/OpsDashboardHeader.vue

@@ -1242,33 +1242,33 @@ function handleToolbarRefresh() {
             <div class="text-3xl font-black text-gray-900 dark:text-white">
               {{ durationP99Ms ?? '-' }}
             </div>
-            <span class="text-xs font-bold text-gray-400">{{ t('admin.ops.msP99') }}</span>
+            <span class="text-xs font-bold text-gray-400">ms (P99)</span>
           </div>
           <div class="mt-3 flex flex-wrap gap-x-3 gap-y-1 text-xs">
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p95') }}</span>
               <span class="font-bold text-gray-900 dark:text-white">{{ durationP95Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p90') }}</span>
               <span class="font-bold text-gray-900 dark:text-white">{{ durationP90Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p50') }}</span>
               <span class="font-bold text-gray-900 dark:text-white">{{ durationP50Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">Avg:</span>
               <span class="font-bold text-gray-900 dark:text-white">{{ durationAvgMs ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">Max:</span>
               <span class="font-bold text-gray-900 dark:text-white">{{ durationMaxMs ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
           </div>
         </div>
@@ -1277,7 +1277,7 @@ function handleToolbarRefresh() {
         <div class="rounded-2xl bg-gray-50 p-4 dark:bg-dark-900" style="order: 5;">
           <div class="flex items-center justify-between">
             <div class="flex items-center gap-1">
-              <span class="text-[10px] font-bold uppercase text-gray-400">{{ t('admin.ops.ttft') }}</span>
+              <span class="text-[10px] font-bold uppercase text-gray-400">TTFT</span>
               <HelpTooltip v-if="!props.fullscreen" :content="t('admin.ops.tooltips.ttft')" />
             </div>
             <button
@@ -1293,33 +1293,33 @@ function handleToolbarRefresh() {
             <div class="text-3xl font-black" :class="isTTFTAboveThreshold(ttftP99Ms) ? 'text-red-600 dark:text-red-400' : getTTFTColor(ttftP99Ms)">
               {{ ttftP99Ms ?? '-' }}
             </div>
-            <span class="text-xs font-bold text-gray-400">{{ t('admin.ops.msP99') }}</span>
+            <span class="text-xs font-bold text-gray-400">ms (P99)</span>
           </div>
           <div class="mt-3 flex flex-wrap gap-x-3 gap-y-1 text-xs">
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p95') }}</span>
               <span class="font-bold" :class="getTTFTColor(ttftP95Ms)">{{ ttftP95Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p90') }}</span>
               <span class="font-bold" :class="getTTFTColor(ttftP90Ms)">{{ ttftP90Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">{{ t('admin.ops.p50') }}</span>
               <span class="font-bold" :class="getTTFTColor(ttftP50Ms)">{{ ttftP50Ms ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">Avg:</span>
               <span class="font-bold" :class="getTTFTColor(ttftAvgMs)">{{ ttftAvgMs ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
             <div class="flex min-w-[60px] items-baseline gap-1 whitespace-nowrap">
               <span class="text-gray-500">Max:</span>
               <span class="font-bold" :class="getTTFTColor(ttftMaxMs)">{{ ttftMaxMs ?? '-' }}</span>
-              <span class="text-gray-400">{{ t('admin.ops.ms') }}</span>
+              <span class="text-gray-400">ms</span>
             </div>
           </div>
         </div>