fix(prefixed_output): add flush to prevent losing final unterminated line

PrefixedOutput#print buffers partial lines until a newline is received.
When the last chunk from a stream does not end with \n (common with
Open3 popen2e EOF), that chunk was discarded. Add #flush to emit the
remaining buffer with the prefix, and call it at the end of all streaming
loops in SshRunner and WireGuardSetup.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/hyperstack/ssh_runner.rb b/lib/hyperstack/ssh_runner.rb
index e4440b6..1384109 100644
--- a/lib/hyperstack/ssh_runner.rb
+++ b/lib/hyperstack/ssh_runner.rb
@@ -25,6 +25,7 @@ module HyperstackVM
           combined << line
           @out.print(line)
         end
+        @out.flush
         return [combined, wait_thr.value]
       end
     end