优化: AI Chat 渲染与无障碍 + 文件查看 + 同步 IO 收口

- 渲染: 结果/过程分离(气泡只放最终结果,过程轮叙述+工具卡收进轨迹卡默认收起可展开——治『流式后正文消失』且不再 N 气泡打扰)
- 渲染 P0: v-memo 定向 dep(只有真正渲染流式块的 item 失效,其余取占位) + renderItems 桶 memo(签名覆盖全消费输入,item 引用稳定) + 指纹 watch 降为 O(1) toolEpoch
- TopBar 三处 O(n) messages computed 合并单次遍历;md 缓存改有界 LRU(除满即全清抖动);useTurnTrace 补 never 穷尽 + default;MessageItem 模板去重
- 无障碍(四批累计): 可点容器键盘化(含 role/tabindex/keydown/aria-expanded) + icon-only aria-label 约 60 处 + 装饰图标 aria-hidden + 52 个滚动容器 overscroll-behavior:contain + 设置开关聚焦可见环 + outline 零补偿站点补 :focus-visible
- UX 走查项: 灵感 IDEA-10/11、知识 KNOW-6/7/9、项目详情 O8、审计 SA-4、设置 SA-6/26/27/28(脏表单/冗余 save/clamp/删除二次确认)
- 文件查看专项: 切工程状态残留 F5/F6、FileTree 去重与展开反馈 F7/F15/F17、切文件头部残留 F18、R 状态着色 F19;FilePreview diff 文件头(---/+++)误当增删渲染修复 + 大纲行高亮死样式修复 + 图片失败文案 i18n 化
- 同步 IO 收口(异步上下文内阻塞): unattended 看板读写改 tokio::fs、fetch_url 探活改 spawn_blocking、http/generate_image 清理改 tokio::fs
- 子代理 P3 批量: 任务书钉扎上限/截断文案区分父子语境/环境画像日期/temperature 可覆盖/model 回退上报/lang 透传
- crate 清理: df-execute·df-types 注释与格式、df-ideas 过时注释、df-nodes subflow 夸大描述、df-project 死变量

src/components/settings/ProviderPanel.vue

@@ -168,16 +168,16 @@
                 <div class="model-tags">
                   <span v-for="md in m.modalities" v-show="!redundantTags.modalities.has(md)" :key="'md-' + md"
                         class="tag tag-modality" :title="$t('settings.tagTooltipModality')">
-                    {{ $t('settings.tagModality.' + md) }}<span class="tag-remove" @click.stop="removeModality(m, md)">×</span>
+                    {{ $t('settings.tagModality.' + md) }}<span class="tag-remove" role="button" tabindex="0" :aria-label="$t('common.delete')" @click.stop="removeModality(m, md)" @keydown.enter.prevent="removeModality(m, md)" @keydown.space.prevent="removeModality(m, md)">×</span>
                   </span>
                   <span v-for="cap in m.capabilities" v-show="!redundantTags.capabilities.has(cap)" :key="'cap-' + cap"
                         class="tag tag-capability" :title="$t('settings.tagTooltipCapability')">
-                    {{ $t('settings.tagCapability.' + cap) }}<span class="tag-remove" @click.stop="removeCapability(m, cap)">×</span>
+                    {{ $t('settings.tagCapability.' + cap) }}<span class="tag-remove" role="button" tabindex="0" :aria-label="$t('common.delete')" @click.stop="removeCapability(m, cap)" @keydown.enter.prevent="removeCapability(m, cap)" @keydown.space.prevent="removeCapability(m, cap)">×</span>
                   </span>
                   <span v-if="m.probe_source && m.probe_source !== 'user_set'" v-show="!redundantTags.sources.has(m.probe_source)"
                         class="tag tag-source" :title="$t('settings.tagTooltipSource')">{{ $t('settings.tagSource.' + m.probe_source) }}</span>
                   <span v-if="m.probe_source === 'user_set'" class="tag tag-source" :title="$t('settings.tagTooltipSource')">{{ $t('settings.tagSource.user_set') }}</span>
-                  <span class="tag-add" :title="$t('settings.addTagTitle')" @click.stop="startAddTag(m)">＋</span>
+                  <span class="tag-add" role="button" tabindex="0" :title="$t('settings.addTagTitle')" :aria-label="$t('settings.addTagTitle')" @click.stop="startAddTag(m)" @keydown.enter.prevent="startAddTag(m)" @keydown.space.prevent="startAddTag(m)">＋</span>
                 </div>
                 <!-- 添加能力内联菜单(点＋展开;选未有的能力/模态即添加) -->
                 <div v-if="addingTagModel === m.model_id" class="add-tag-menu">
@@ -293,7 +293,10 @@ const providerForm = reactive({
  */
 const redundantTags = computed(() => {
   const models = providerForm.models
-  if (models.length === 0) return { modalities: new Set<string>(), capabilities: new Set<string>(), sources: new Set<string>() }
+  // SA-6: 去冗余的前提是「模型间对比」——仅 1 个模型时它的所有标签都满足「全模型共有」,
+  // 无脑隐藏会把唯一模型的能力标签全抹掉(行内空白,用户看不到该模型能力)。
+  // 故 ≥2 个模型起才去冗余;0/1 个一律全显(sources 分支本就 <2 直接放行,此处对齐)。
+  if (models.length < 2) return { modalities: new Set<string>(), capabilities: new Set<string>(), sources: new Set<string>() }
   const common = (pick: (m: ModelConfig) => string[]) => {
     const sets = models.map(m => new Set(pick(m)))
     const first = sets[0]