feat(ui): rename 图生图→参考图 with count; distinguish video 首尾帧 vs 参考图

- model list: any model with max_reference_images>0 shows 首尾帧 N (frame mode)
  or 参考图 N (asset/other); drop the count-less "图生图" label
- ModelFormModal / TestModal: capability labels use 参考图 (not 图生图)
- grok-video uses reference_mode=asset (参考图), runway/adobe video stay frame (首尾帧)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/views/ModelsView.vue

@@ -211,12 +211,12 @@ onMounted(loadModels)
                  video frame mode, supported resolutions for video. -->
             <td class="px-3 py-3.5 align-middle">
               <div class="flex flex-wrap items-center gap-1 text-[11px]">
-                <span v-if="m.type === 'image' && m.image_to_image"
-                      class="cap-chip cap-emerald">图生图</span>
-                <!-- 参考图 is a capability like 图生图 — same emerald style, shown first -->
-                <span v-if="m.type === 'video' && m.max_reference_images > 0"
+                <!-- reference capability with count: frame mode = 首尾帧, else 参考图 -->
+                <span v-if="m.max_reference_images > 0"
                       class="cap-chip cap-emerald"
-                      :title="REF_MODE_LABEL[m.reference_mode]">参考图 {{ m.max_reference_images }}</span>
+                      :title="REF_MODE_LABEL[m.reference_mode]">{{ m.reference_mode === 'frame' ? '首尾帧' : '参考图' }} {{ m.max_reference_images }}</span>
+                <span v-else-if="m.type === 'image' && m.image_to_image"
+                      class="cap-chip cap-emerald">参考图</span>
                 <span v-if="m.type === 'video'" v-for="r in (m.resolutions || [])" :key="'vr'+r"
                       class="cap-chip cap-slate">{{ r }}</span>
                 <span v-if="(m.type === 'image' && !(m.ratios || []).length && !m.image_to_image) ||