feat(backup): add independent backup panel, configurable policy, and rename support

Extract backup & restore into a standalone AccordionItem in Advanced settings.
Add configurable auto-backup interval (disabled/6h/12h/24h/48h/7d) and retention
count (3-50) via settings. Add per-backup rename with inline editing UI.

src/i18n/locales/en.json

@@ -230,7 +230,11 @@
       },
       "data": {
         "title": "Data Management",
-        "description": "Import/export local configurations and backup/restore"
+        "description": "Import and export local configuration data"
+      },
+      "backup": {
+        "title": "Backup & Restore",
+        "description": "Manage automatic backups, view and restore database snapshots"
       },
       "cloudSync": {
         "title": "Cloud Sync",
@@ -306,7 +310,16 @@
       "confirmMessage": "Restoring this backup will overwrite the current database. A safety backup will be created first.",
       "restoreSuccess": "Restore successful! Safety backup created",
       "restoreFailed": "Restore failed",
-      "safetyBackupId": "Safety Backup ID"
+      "safetyBackupId": "Safety Backup ID",
+      "intervalLabel": "Auto-backup Interval",
+      "retainLabel": "Backup Retention",
+      "intervalDisabled": "Disabled",
+      "intervalHours": "{{hours}} hours",
+      "intervalDays": "{{days}} days",
+      "rename": "Rename",
+      "renameSuccess": "Backup renamed",
+      "renameFailed": "Rename failed",
+      "namePlaceholder": "Enter new name"
     },
     "webdavSync": {
       "title": "WebDAV Cloud Sync",

src/i18n/locales/ja.json

@@ -230,7 +230,11 @@
       },
       "data": {
         "title": "データ管理",
-        "description": "ローカル設定のインポート/エクスポートとバックアップ/復元"
+        "description": "ローカル設定データのインポートとエクスポート"
+      },
+      "backup": {
+        "title": "バックアップと復元",
+        "description": "自動バックアップの管理、データベーススナップショットの表示と復元"
       },
       "cloudSync": {
         "title": "クラウド同期",
@@ -306,7 +310,16 @@
       "confirmMessage": "このバックアップを復元すると現在のデータベースが上書きされます。安全バックアップが先に作成されます。",
       "restoreSuccess": "復元成功！安全バックアップが作成されました",
       "restoreFailed": "復元に失敗しました",
-      "safetyBackupId": "安全バックアップID"
+      "safetyBackupId": "安全バックアップID",
+      "intervalLabel": "自動バックアップ間隔",
+      "retainLabel": "バックアップ保持数",
+      "intervalDisabled": "無効",
+      "intervalHours": "{{hours}} 時間",
+      "intervalDays": "{{days}} 日",
+      "rename": "名前変更",
+      "renameSuccess": "バックアップの名前を変更しました",
+      "renameFailed": "名前変更に失敗しました",
+      "namePlaceholder": "新しい名前を入力"
     },
     "webdavSync": {
       "title": "WebDAV クラウド同期",

src/i18n/locales/zh.json

@@ -230,7 +230,11 @@
       },
       "data": {
         "title": "数据管理",
-        "description": "导入导出本地配置与备份恢复"
+        "description": "导入和导出本地配置数据"
+      },
+      "backup": {
+        "title": "备份与恢复",
+        "description": "管理自动备份，查看和恢复数据库快照"
       },
       "cloudSync": {
         "title": "云同步",
@@ -306,7 +310,16 @@
       "confirmMessage": "恢复到此备份将覆盖当前数据库。恢复前会自动创建安全备份。",
       "restoreSuccess": "恢复成功！安全备份已创建",
       "restoreFailed": "恢复失败",
-      "safetyBackupId": "安全备份ID"
+      "safetyBackupId": "安全备份ID",
+      "intervalLabel": "自动备份间隔",
+      "retainLabel": "备份保留数量",
+      "intervalDisabled": "禁用",
+      "intervalHours": "{{hours}} 小时",
+      "intervalDays": "{{days}} 天",
+      "rename": "重命名",
+      "renameSuccess": "备份重命名成功",
+      "renameFailed": "重命名失败",
+      "namePlaceholder": "输入新名称"
     },
     "webdavSync": {
       "title": "WebDAV 云同步",