fix: wait for final log flush before closing deploymentLogWriter (closes #4)

internal/service/deploy/deploy.go

@@ -78,6 +78,7 @@ type deploymentLogWriter struct {
 	lineBuffer bytes.Buffer // buffer for incomplete lines
 	mu         sync.Mutex
 	done       chan struct{}
+	flushed    sync.WaitGroup // waits for flush goroutine to finish
 	flushCtx   context.Context //nolint:containedctx // needed for async flush goroutine
 }
 
@@ -87,6 +88,7 @@ func newDeploymentLogWriter(ctx context.Context, deployment *models.Deployment)
 		done:       make(chan struct{}),
 		flushCtx:   ctx,
 	}
+	w.flushed.Add(1)
 	go w.runFlushLoop()
 
 	return w
@@ -128,12 +130,15 @@ func (w *deploymentLogWriter) Write(p []byte) (int, error) {
 	return len(p), nil
 }
 
-// Close stops the flush loop and performs a final flush.
+// Close stops the flush loop, waits for the final flush to complete.
 func (w *deploymentLogWriter) Close() {
 	close(w.done)
+	w.flushed.Wait()
 }
 
 func (w *deploymentLogWriter) runFlushLoop() {
+	defer w.flushed.Done()
+
 	ticker := time.NewTicker(logFlushInterval)
 	defer ticker.Stop()