Fix flaky SpinnerObserver tests with WaitGroup sync

Add sync.WaitGroup to SpinnerObserver so stopSpinner() blocks until the
animate() goroutine finishes its cleanup write, eliminating the race that
caused TestSpinnerObserver_MultiplePhases flakiness. Remove all
time.Sleep calls from tests since synchronization is now deterministic.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JAORMX

internal/infra/progress/spinner.go

@@ -26,6 +26,7 @@ type SpinnerObserver struct {
 	out  io.Writer
 	mu   sync.Mutex
 	stop chan struct{} // nil when no spinner is active
+	wg   sync.WaitGroup
 
 	successStyle lipgloss.Style
 	warnStyle    lipgloss.Style
@@ -53,6 +54,7 @@ func (s *SpinnerObserver) Start(_ progress.Phase, msg string) {
 	s.stop = stop
 	s.mu.Unlock()
 
+	s.wg.Add(1)
 	go s.animate(msg, stop)
 }
 
@@ -81,9 +83,11 @@ func (s *SpinnerObserver) stopSpinner() {
 		s.stop = nil
 	}
 	s.mu.Unlock()
+	s.wg.Wait()
 }
 
 func (s *SpinnerObserver) animate(msg string, stop <-chan struct{}) {
+	defer s.wg.Done()
 	ticker := time.NewTicker(80 * time.Millisecond)
 	defer ticker.Stop()
 

internal/infra/progress/spinner_test.go

@@ -7,7 +7,6 @@ import (
 	"bytes"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 
@@ -57,8 +56,6 @@ func TestSpinnerObserver_StartThenComplete(t *testing.T) {
 	obs := NewSpinnerObserver(&buf)
 
 	obs.Start(progress.PhaseStartingVM, "Starting VM...")
-	// Give the goroutine a moment to emit at least one frame.
-	time.Sleep(150 * time.Millisecond)
 	obs.Complete("VM started")
 
 	output := buf.String()
@@ -73,11 +70,9 @@ func TestSpinnerObserver_MultiplePhases(t *testing.T) {
 	obs := NewSpinnerObserver(&buf)
 
 	obs.Start(progress.PhaseResolvingAgent, "Resolving...")
-	time.Sleep(100 * time.Millisecond)
 	obs.Complete("Resolved")
 
 	obs.Start(progress.PhaseStartingVM, "Starting...")
-	time.Sleep(100 * time.Millisecond)
 	obs.Complete("Started")
 
 	output := buf.String()