refactor: 前端本地偏好统一为公共存储层

- 新增 frontend/src/utils/storageKeys.ts 集中维护存储键常量并登记旧键迁移
- 新增 frontend/src/utils/storage.ts 统一 localStorage/sessionStorage 读写与异常容错
- 新增 frontend/src/composables/usePreference.ts 提供 useStringPreference 响应式字符串偏好
- 新增 frontend/src/utils/transactionFilterPrefs.ts 抽出收支筛选偏好字段定义与共享读写
- 存储键统一以 finance. 前缀命名，locale、emailBill.tab、logs.tab 迁移到新键并自动迁移旧值
- 各页面与组件改用公共层，移除重复的 try/catch 与跨组件重复的序列化逻辑
- 认证凭据 token 属登录状态，保持原键名不纳入 finance. 前缀

frontend/src/components/FloatingPanel.vue

@@ -3,6 +3,7 @@
 import { ref, watch, onBeforeUnmount, nextTick } from 'vue'
 import { NButton, NIcon } from 'naive-ui'
 import { CloseOutline } from '@vicons/ionicons5'
+import { readJson, writeJson } from '../utils/storage'
 
 /** 浮窗位置与尺寸 */
 interface PanelRect {
@@ -67,25 +68,20 @@ function clampRect() {
 /** 读取持久化的位置与尺寸，非法值回退默认并居中 */
 function loadRect() {
   if (props.storageKey) {
-    try {
-      const raw = localStorage.getItem(props.storageKey)
-      const parsed = raw ? JSON.parse(raw) : null
-      const x = Number(parsed?.x)
-      const y = Number(parsed?.y)
-      const width = Number(parsed?.width)
-      const height = Number(parsed?.height)
-      if ([x, y, width, height].every((n) => Number.isFinite(n))) {
-        rect.value = {
-          x,
-          y,
-          width: Math.max(props.minWidth, width),
-          height: Math.max(props.minHeight, height),
-        }
-        clampRect()
-        return
+    const parsed = readJson<Partial<PanelRect> | null>(props.storageKey, null)
+    const x = Number(parsed?.x)
+    const y = Number(parsed?.y)
+    const width = Number(parsed?.width)
+    const height = Number(parsed?.height)
+    if ([x, y, width, height].every((n) => Number.isFinite(n))) {
+      rect.value = {
+        x,
+        y,
+        width: Math.max(props.minWidth, width),
+        height: Math.max(props.minHeight, height),
       }
-    } catch {
-      // 忽略读取失败
+      clampRect()
+      return
     }
   }
   rect.value = defaultRect()
@@ -94,11 +90,7 @@ function loadRect() {
 /** 持久化位置与尺寸，忽略存储异常 */
 function saveRect() {
   if (!props.storageKey) return
-  try {
-    localStorage.setItem(props.storageKey, JSON.stringify(rect.value))
-  } catch {
-    // 忽略写入失败
-  }
+  writeJson(props.storageKey, rect.value)
 }
 
 // 拖拽状态

frontend/src/components/TransactionRelationEditorModal.vue

@@ -9,9 +9,11 @@ import type { TransactionGroup, TransactionRelationType, TransactionGroupPayload
 import { getTransactionPage } from '../api/transaction'
 import { getAiConfig, parseRelationByAi } from '../api/ai'
 import { getChannelLabel } from '../utils/channel'
+import { readString, writeString } from '../utils/storage'
+import { STORAGE_KEYS } from '../utils/storageKeys'
 
 /** 关系类型偏好存储键（界面偏好统一以 finance. 前缀命名） */
-const RELATION_TYPE_KEY = 'finance.transaction.relationType'
+const RELATION_TYPE_KEY = STORAGE_KEYS.transactionRelationType
 
 const props = defineProps<{
   /** 弹窗显示状态 */
@@ -79,21 +81,13 @@ onMounted(loadAiConfig)
 
 /** 读取上次使用的关系类型偏好，非法值或异常回退 PARENT_CHILD */
 function loadPreferredRelationType(): TransactionRelationType {
-  try {
-    const saved = localStorage.getItem(RELATION_TYPE_KEY)
-    return saved === 'PARENT_CHILD' || saved === 'SIBLING' ? saved : 'PARENT_CHILD'
-  } catch (e) {
-    return 'PARENT_CHILD'
-  }
+  const saved = readString(RELATION_TYPE_KEY)
+  return saved === 'PARENT_CHILD' || saved === 'SIBLING' ? saved : 'PARENT_CHILD'
 }
 
 /** 保存关系类型偏好，忽略存储异常 */
 function savePreferredRelationType(type: TransactionRelationType) {
-  try {
-    localStorage.setItem(RELATION_TYPE_KEY, type)
-  } catch (e) {
-    // 忽略存储异常
-  }
+  writeString(RELATION_TYPE_KEY, type)
 }
 
 /** 加载关系名称历史（按当前关系类型过滤） */