feat: import SQLite migration dumps through the PostgreSQL panel restore

The SQLite panel's Download Migration produces a portable SQL text dump
advertised as seeding a PostgreSQL panel, but the PostgreSQL Restore only
accepted pg_dump custom archives, so the migration file was rejected with
'Invalid file' even though the upload picker asked for .dump. importDB now
sniffs the upload header: PGDMP archives keep the pg_restore path, while
raw SQLite databases (.db) and SQL text migration dumps are rebuilt,
integrity-checked, and copied into PostgreSQL with the same MigrateData
engine as 'x-ui migrate-db --dsn'. The restore picker accepts .dump/.db on
PostgreSQL and the backup modal texts describe the accepted formats in
every locale.

internal/web/translation/zh-CN.json

@@ -269,11 +269,11 @@
       "readDatabaseError": "读取数据库时出错",
       "getDatabaseError": "检索数据库时出错",
       "getConfigError": "检索配置文件时出错",
-      "backupPostgresNote": "此面板运行在 PostgreSQL 上。「备份」会下载一个 pg_dump 归档（.dump），「恢复」会通过 pg_restore 重新载入。服务器需要安装 PostgreSQL 客户端工具（pg_dump 和 pg_restore）。",
+      "backupPostgresNote": "此面板运行在 PostgreSQL 上。「备份」会下载一个 pg_dump 归档（.dump），「恢复」会通过 pg_restore 重新载入。「恢复」也接受 SQLite 数据库（.db）或 SQLite 迁移导出文件，并将其数据导入 PostgreSQL。服务器需要安装 PostgreSQL 客户端工具（pg_dump 和 pg_restore）。",
       "exportDatabasePgDesc": "点击将当前数据库的 PostgreSQL 转储（.dump）下载到您的设备。",
-      "importDatabasePgDesc": "点击选择并上传 .dump 文件以恢复您的 PostgreSQL 数据库。此操作将替换所有当前数据。",
+      "importDatabasePgDesc": "点击选择并上传 PostgreSQL 备份（.dump）、SQLite 数据库（.db）或 SQLite 迁移导出文件以恢复您的数据库。此操作将替换所有当前数据。",
       "migrationDownload": "下载迁移文件",
-      "migrationDownloadDesc": "点击下载当前 SQLite 数据库的可移植 .dump（SQL 文本）导出文件。",
+      "migrationDownloadDesc": "点击下载当前 SQLite 数据库的可移植 .dump（SQL 文本）导出文件。它可以通过「恢复」还原到运行 PostgreSQL 的面板中。",
       "migrationDownloadPgDesc": "点击下载由 PostgreSQL 数据构建的 .db SQLite 数据库，可用于在 SQLite 上运行本面板。"
     },
     "inbounds": {