fix: 优化移动端工作台筛选与工具栏

将形态图片状态筛选合并为下拉框，统一筛选容器内边距并调整背景。重新排列分镜与镜头生产移动端工具栏，隐藏重复统计并补充交互测试。

src/features/subject-images/SubjectImagesPage.vue

@@ -137,8 +137,14 @@ const search = ref('')
 /** 切换排版复用同一份卡片和查询结果，不重新读取图库或清空筛选。 */
 const layout = ref<GalleryLayout>('grid')
 const module = ref('all')
-const onlyMissing = ref(false)
-const onlyStale = ref(false)
+/** 形态图片状态筛选；单选下拉避免移动端复选项占据两行。 */
+type ImageStatusFilter = 'all' | 'missing' | 'stale'
+const statusFilter = ref<ImageStatusFilter>('all')
+const statusFilterOptions: Array<{ label: string; value: ImageStatusFilter }> = [
+    { label: '全部状态', value: 'all' },
+    { label: '缺少主图', value: 'missing' },
+    { label: '身份过期', value: 'stale' }
+]
 /** 保存每张卡片的尺寸观察器，切换回网格时及时释放。 */
 const masonryCardObservers = new WeakMap<HTMLElement, ResizeObserver>()
 
@@ -223,8 +229,8 @@ const filtered = computed(() =>
         form =>
             (!targetFormId.value || form.id === targetFormId.value) &&
             (module.value === 'all' || form.subject.module === module.value) &&
-            (!onlyMissing.value || !primaryImage(form.images)) &&
-            (!onlyStale.value || isPrimaryIdentityStale(form)) &&
+            (statusFilter.value !== 'missing' || !primaryImage(form.images)) &&
+            (statusFilter.value !== 'stale' || isPrimaryIdentityStale(form)) &&
             `${form.subject.name} ${form.subject.ref} ${form.name}`
                 .toLowerCase()
                 .includes(search.value.trim().toLowerCase())
@@ -235,8 +241,7 @@ watch(
     () => {
         search.value = targetFormId.value ? '' : queryText(route.query.subjectRef)
         module.value = 'all'
-        onlyMissing.value = false
-        onlyStale.value = false
+        statusFilter.value = 'all'
         galleryOpen.value = false
         generateOpen.value = false
         promptOpen.value = false
@@ -272,8 +277,7 @@ function exportReceipt() {
 function resetFilters() {
     search.value = ''
     module.value = 'all'
-    onlyMissing.value = false
-    onlyStale.value = false
+    statusFilter.value = 'all'
     void router.replace({
         query: { ...route.query, subjectFormId: undefined, subjectRef: undefined, sourceShotId: undefined }
     })
@@ -298,8 +302,7 @@ async function showStaleForms() {
     })
     search.value = ''
     module.value = 'all'
-    onlyMissing.value = false
-    onlyStale.value = true
+    statusFilter.value = 'stale'
 }
 </script>
 
@@ -571,10 +574,12 @@ async function showStaleForms() {
                                     { label: String('道具'), value: 'prop' }
                                 ]"
                             ></NSelect>
-                            <div class="filter-toggles">
-                                <NCheckbox v-model:checked="onlyMissing">仅看缺少主图</NCheckbox>
-                                <NCheckbox v-model:checked="onlyStale">仅看身份过期</NCheckbox>
-                            </div>
+                            <NSelect
+                                v-model:value="statusFilter"
+                                :options="statusFilterOptions"
+                                aria-label="筛选图片状态"
+                                class="status-filter"
+                            />
                             <div class="form-image-display-controls">
                                 <span class="filter-result-count">{{ filtered.length }} 个形态</span>
                                 <div class="gallery-layout-switch" role="group" aria-label="图库显示方式">
@@ -853,7 +858,8 @@ async function showStaleForms() {
     @apply [overflow-anchor:none];
 }
 .form-image-filter-region {
-    @apply my-4 py-[5px] px-4 bg-(--app-subtle);
+    @apply my-4 p-3;
+    background: color-mix(in srgb, var(--app-subtle) 96%, white);
     container-type: inline-size;
 }
 .form-image-toolbar {
@@ -875,17 +881,11 @@ async function showStaleForms() {
     @apply min-w-0;
 }
 .form-image-filters {
-    @apply grid grid-cols-[minmax(200px,_360px)_152px_minmax(260px,_1fr)_auto] items-center gap-y-3 gap-x-4;
+    @apply grid grid-cols-[minmax(200px,_360px)_152px_160px_auto] items-center gap-y-3 gap-x-4;
 }
 .form-image-filters > * {
     @apply min-w-0;
 }
-.filter-toggles {
-    @apply flex items-center flex-wrap gap-y-2.5 gap-x-4 text-xs;
-}
-.filter-toggles .n-checkbox__label {
-    @apply whitespace-nowrap;
-}
 .filter-result-count {
     @apply justify-self-end text-muted text-xs whitespace-nowrap;
 }
@@ -905,14 +905,20 @@ async function showStaleForms() {
     .form-image-filters {
         @apply grid-cols-[minmax(0,_1fr)_152px];
     }
+    .status-filter {
+        @apply col-start-1 row-start-2;
+    }
     .form-image-display-controls {
-        @apply col-[1/-1];
+        @apply col-start-2 row-start-2;
     }
 }
 @container (max-width: 460px) {
     .form-image-filters {
         @apply grid-cols-[minmax(0,_1fr)_120px] gap-x-2.5;
     }
+    .filter-result-count {
+        @apply hidden;
+    }
 }
 .asset-impact-context {
     @apply flex flex-col gap-2.5 py-[5px] px-4 bg-(--app-subtle) m-0 min-w-0;