feat: 更新 FaceFilterSettings TypeScript 类型定义为三段式统一结构

变更内容：
- 创建 src/types/faceFilter.ts 类型定义文件
- 新增 UiFilterRules, ProcessingThresholds, TraceSettings 三个子结构
- 更新 FaceFilterSettings 为三段式统一结构
- min_confidence 范围从 0-100 改为 0.0-1.0
- min_size 重命名为 min_bbox_size
- 新增字段: max_confidence, max_bbox_size, source, backend_status

向后兼容性：
- FaceFilterSettingsMigration.fromLegacy() 自动转换旧格式
- FaceFilterSettingsMigration.defaults() 提供默认值
- 保留向后兼容字段（deprecated 标记）

更新文件：
- src/composables/useFaceFilter.ts: 使用新类型，更新变量名
- src/components/FaceFilterPanel.vue: 更新导入和变量引用
- docs/FACE_FILTER_SETTINGS_MIGRATION_GUIDE.md: 完整迁移指南

测试：
- ✅ TypeScript 编译通过
- ✅ Vite build 成功

对应 Core API commit: 86c776ce

src/components/FaceFilterPanel.vue

@@ -108,7 +108,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="singleFrameSettings.single_frame_trace_vlm_enabled"
+              v-model="faceFilterSettings.single_frame_trace_vlm_enabled"
               @change="markModified"
             />
             VLM Processing
@@ -120,7 +120,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="singleFrameSettings.single_frame_trace_group_enabled"
+              v-model="faceFilterSettings.single_frame_trace_group_enabled"
               @change="markModified"
             />
             Face Groups
@@ -132,7 +132,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="singleFrameSettings.single_frame_trace_unassigned_enabled"
+              v-model="faceFilterSettings.single_frame_trace_unassigned_enabled"
               @change="markModified"
             />
             Unassigned List
@@ -144,7 +144,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="singleFrameSettings.single_trace_group_filter_enabled"
+              v-model="faceFilterSettings.single_trace_group_filter_enabled"
               @change="markModified"
             />
             Single Trace Groups
@@ -154,19 +154,19 @@
         
         <div class="section-actions">
           <div class="auto-save-hint">
-            {{ singleFrameSettingsLoading ? '⏳ Saving...' : '✓ Auto-saved' }}
+            {{ faceFilterSettingsLoading ? '⏳ Saving...' : '✓ Auto-saved' }}
           </div>
           <button 
             class="action-btn"
             @click="handleResetSingleFrame"
-            :disabled="singleFrameSettingsLoading"
+            :disabled="faceFilterSettingsLoading"
           >
             Reset to Default
           </button>
         </div>
         
-        <div v-if="singleFrameSettingsError" class="error-message">
-          ❌ {{ singleFrameSettingsError }}
+        <div v-if="faceFilterSettingsError" class="error-message">
+          ❌ {{ faceFilterSettingsError }}
         </div>
       </div>
       
@@ -220,7 +220,7 @@
 
 <script setup lang="ts">
 import { ref, watch, onBeforeUnmount } from 'vue';
-import { useFaceFilter, type QuickFilterRules } from '../composables/useFaceFilter';
+import { useFaceFilter, type UiFilterRules } from '../composables/useFaceFilter';
 
 const props = defineProps<{
   fileUuid: string;
@@ -242,10 +242,10 @@ const {
   updateRules,
   applyBackendFilter,
   resetToDefault,
-  singleFrameSettings,
-  singleFrameSettingsLoading,
-  singleFrameSettingsError,
-  singleFrameSettingsModified,
+  faceFilterSettings,
+  faceFilterSettingsLoading,
+  faceFilterSettingsError,
+  faceFilterSettingsModified,
   loadSingleFrameSettings,
   resetSingleFrameSettings,
   markSingleFrameSettingsModified,
@@ -291,7 +291,7 @@ watch(showPanel, (show) => {
   }
 });
 
-watch(singleFrameSettingsModified, (newVal, oldVal) => {
+watch(faceFilterSettingsModified, (newVal, oldVal) => {
   if (oldVal === true && newVal === false) {
     emit('settings-updated');
   }