flush buffered output before spawning inherited-stdout children (stream/streamLocal) so nina headers aren't reordered after journalctl/systemctl output

@@ -38,6 +38,9 @@3838 3939 // Run a process and stream its output to the terminal (inherit stdio).4040 pub fn stream(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, cmd: []const []const u8) !u8 {41+    // The child inherits stdout and writes directly to the fd; flush any buffered42+    // nina header first so it isn't reordered after the child's output.43+    output.flush();4144     const argv = try buildArgv(gpa, machine, cmd);4245     defer if (!machine.local) gpa.free(argv);4346 @@ -64,6 +67,7 @@6467 6568 // Stream a local process with inherited stdio (no SSH routing — for nix commands).6669 pub fn streamLocal(io: std.Io, cmd: []const []const u8) !u8 {70+    output.flush();6771     var child = std.process.spawn(io, .{6872         .argv = cmd,6973         .stdin = .inherit,