fix: 移除 FaceFilterSettings 重复字段，与 Rust 端结构一致

问题修正：
- 移除 FaceFilterSettings 中的重复字段
- 简化为三段式结构（ui_filter_rules, processing_thresholds, trace_settings）
- 新增 version 字段用于版本控制
- 删除 useFaceFilter.ts 中的 rules 变量
- 重命名 faceFilterSettings 为 settings
- 更新所有访问方式为 settings.value.ui_filter_rules.*

变更内容：
1. src/types/faceFilter.ts
   - FaceFilterSettings 只保留三段式结构
   - fromLegacy() 和 defaults() 不再返回重复字段

2. src/composables/useFaceFilter.ts
   - 删除 rules 变量（不再需要）
   - 删除 defaultRules 常量
   - 重命名 faceFilterSettings 为 settings
   - 更新 localStorage 逻辑保存完整 settings
   - 所有访问改为 settings.value.ui_filter_rules.*

3. src/components/FaceFilterPanel.vue
   - 更新 v-model 绑定为 settings.trace_settings.*
   - 更新解构，删除 rules
   - 更新所有访问为 settings.ui_filter_rules.*

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

对应 Core API: 86c776ce
修正文档: docs/FACE_FILTER_TYPES_FIX_REQUIRED.md

src/components/FaceFilterPanel.vue

@@ -57,7 +57,7 @@
         <label>Confidence:</label>
         <input 
           type="number" 
-          v-model.number="rules.min_confidence"
+          v-model.number="settings.ui_filter_rules.min_confidence"
           @change="onRuleChange"
           min="0" 
           max="1" 
@@ -72,7 +72,7 @@
         <label>Bbox Size:</label>
         <input 
           type="number" 
-          v-model.number="rules.min_bbox_size"
+          v-model.number="settings.ui_filter_rules.min_bbox_size"
           @change="onRuleChange"
           min="0" 
           step="10"
@@ -84,7 +84,7 @@
       
       <div class="filter-row">
         <label>Source:</label>
-        <select v-model="rules.source" @change="onRuleChange" class="filter-select">
+        <select v-model="settings.ui_filter_rules.source" @change="onRuleChange" class="filter-select">
           <option value="all">All</option>
           <option value="apple_vision">Apple Vision</option>
           <option value="mediapipe">MediaPipe</option>
@@ -93,7 +93,7 @@
       
       <div class="filter-row">
         <label>Backend Status:</label>
-        <select v-model="rules.backend_status" @change="onRuleChange" class="filter-select">
+        <select v-model="settings.ui_filter_rules.backend_status" @change="onRuleChange" class="filter-select">
           <option value="all">All</option>
           <option value="accept">Accept</option>
           <option value="review">Review</option>
@@ -108,7 +108,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="faceFilterSettings.single_frame_trace_vlm_enabled"
+              v-model="settings.trace_settings.single_frame_trace_vlm_enabled"
               @change="markModified"
             />
             VLM Processing
@@ -120,7 +120,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="faceFilterSettings.single_frame_trace_group_enabled"
+              v-model="settings.trace_settings.single_frame_trace_group_enabled"
               @change="markModified"
             />
             Face Groups
@@ -132,7 +132,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="faceFilterSettings.single_frame_trace_unassigned_enabled"
+              v-model="settings.trace_settings.single_frame_trace_unassigned_enabled"
               @change="markModified"
             />
             Unassigned List
@@ -144,7 +144,7 @@
           <label class="checkbox-label">
             <input 
               type="checkbox" 
-              v-model="faceFilterSettings.single_trace_group_filter_enabled"
+              v-model="settings.trace_settings.single_trace_group_filter_enabled"
               @change="markModified"
             />
             Single Trace Groups
@@ -154,19 +154,19 @@
         
         <div class="section-actions">
           <div class="auto-save-hint">
-            {{ faceFilterSettingsLoading ? '⏳ Saving...' : '✓ Auto-saved' }}
+            {{ settingsLoading ? '⏳ Saving...' : '✓ Auto-saved' }}
           </div>
           <button 
             class="action-btn"
             @click="handleResetSingleFrame"
-            :disabled="faceFilterSettingsLoading"
+            :disabled="settingsLoading"
           >
             Reset to Default
           </button>
         </div>
         
-        <div v-if="faceFilterSettingsError" class="error-message">
-          ❌ {{ faceFilterSettingsError }}
+        <div v-if="settingsError" class="error-message">
+          ❌ {{ settingsError }}
         </div>
       </div>
       
@@ -232,7 +232,6 @@ const emit = defineEmits<{
 
 const {
   mode,
-  rules,
   filterResult,
   filterStats,
   loading,
@@ -242,14 +241,14 @@ const {
   updateRules,
   applyBackendFilter,
   resetToDefault,
-  faceFilterSettings,
-  faceFilterSettingsLoading,
-  faceFilterSettingsError,
-  faceFilterSettingsModified,
+  settings,
+  settingsLoading,
+  settingsError,
+  settingsModified,
   loadSingleFrameSettings,
   resetSingleFrameSettings,
   markSingleFrameSettingsModified,
-  cleanupAutoSave
+  cleanupAutoSave,
 } = useFaceFilter();
 
 const showPanel = ref(false);
@@ -259,7 +258,7 @@ function togglePanel() {
 }
 
 function onRuleChange() {
-  updateRules(rules.value);
+  updateRules(settings.value.ui_filter_rules);
 }
 
 async function handleApplyBackend() {
@@ -291,7 +290,7 @@ watch(showPanel, (show) => {
   }
 });
 
-watch(faceFilterSettingsModified, (newVal, oldVal) => {
+watch(settingsModified, (newVal, oldVal) => {
   if (oldVal === true && newVal === false) {
     emit('settings-updated');
   }