fix(dashboard): MySQL backups with a tcp://, unix:// or pipe:// mysql_host

mysqldump was given --host=tcp --port=//host:port for the tcp:// form the servers accept, so
backups failed. Read mysql_host the way the servers connect with it: tcp://host:port (a trailing
/database is dropped), unix:// as --socket and pipe:// as a named pipe.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDashboardServer/routes/BackupFiles.h

@@ -39,7 +39,7 @@ namespace BackupFiles {
 	struct DumpCommand {
 		std::string program;
 		std::string optionsFile;
-		std::string host; // host or host:port
+		std::string host; // mysql_host: host, host:port, tcp://host:port, unix://socket or pipe://name
 		std::string database;
 		std::string target;
 		std::string errorFile; // mysqldump's messages; never mixed into the dump, where they would break a restore