Refresh rate is honoured exactly everywhere: no list floor, sampler up to 10 s, server caches reduced to coalescing only

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/services/services.go

@@ -107,7 +107,7 @@ func run(ctx context.Context, args ...string) (string, error) {
 // Cached for a few seconds because the UI polls it.
 func (m *Manager) List(ctx context.Context) ([]Unit, error) {
 	m.mu.Lock()
-	if time.Since(m.cacheAt) < 4*time.Second && m.cache != nil {
+	if time.Since(m.cacheAt) < 200*time.Millisecond && m.cache != nil { // coalesce simultaneous clients only
 		c := m.cache
 		m.mu.Unlock()
 		return c, nil