Add isolated Remote speech synthesis and typed rendering

Preserve literal whitespace and resolved spelling/language state across complete Remote speech assemblies. Isolate cancellation from local status and echo, retire handles on configuration changes or rendering failure, and cover metadata preparation cancellation with private SSIP fixtures.

Verified focused application and backend race tests, ten repetitions of isolated-client/rendering cases, shared speech regressions, affected-package vet, reader build and Tentacles checks. Incoming mailbox integration, local priority and live audible acceptance remain pending.

internal/app/configured_speaker.go

@@ -31,6 +31,7 @@ type configuredSpeaker struct {
 	mu       sync.RWMutex
 	update   sync.Mutex
 	active   configuredVoice
+	remote   *remoteSpeechVoice
 	socket   string
 	settings config.Settings
 	closed   bool
@@ -70,10 +71,15 @@ func (speaker *configuredSpeaker) UpdateConfiguration(ctx context.Context, setti
 		}
 		hardware.settings = settings
 		hardware.mu.Unlock()
+		speaker.retire_remote_voice(settings)
 		return nil
 	}
 	if software, ok := current.(*echoSpeaker); ok && settings.SpeechServerFactory != "hardwarefactory" {
-		return software.UpdateConfiguration(ctx, settings)
+		if err := software.UpdateConfiguration(ctx, settings); err != nil {
+			return err
+		}
+		speaker.retire_remote_voice(settings)
+		return nil
 	}
 	var candidate configuredVoice
 	if settings.SpeechServerFactory == "hardwarefactory" {
@@ -99,8 +105,8 @@ func (speaker *configuredSpeaker) UpdateConfiguration(ctx context.Context, setti
 		}
 	}
 	speaker.active = candidate
-	speaker.settings = settings
 	speaker.mu.Unlock()
+	speaker.retire_remote_voice(settings)
 	// The new backend is committed. A retired connection's cleanup error must
 	// not report this successful swap as a rejected preferences transaction.
 	if current != nil {
@@ -182,23 +188,34 @@ func (speaker *configuredSpeaker) speak_uninterruptible(ctx context.Context, tex
 func (speaker *configuredSpeaker) Cancel(ctx context.Context) error {
 	speaker.mu.RLock()
 	voice := speaker.active
+	remote := speaker.remote
 	speaker.mu.RUnlock()
-	if voice == nil {
-		return nil
+	var result error
+	if voice != nil {
+		result = voice.Cancel(ctx)
 	}
-	return voice.Cancel(ctx)
+	if remote != nil {
+		result = errors.Join(result, remote.Cancel(ctx))
+	}
+	return result
 }
 func (speaker *configuredSpeaker) Close(ctx context.Context) error {
 	speaker.update.Lock()
 	defer speaker.update.Unlock()
 	speaker.mu.Lock()
 	voice := speaker.active
+	remote := speaker.remote
 	speaker.active, speaker.closed = nil, true
+	speaker.remote = nil
 	speaker.mu.Unlock()
-	if voice == nil {
-		return nil
+	var result error
+	if remote != nil {
+		result = remote.Close(ctx)
 	}
-	return voice.Close(ctx)
+	if voice == nil {
+		return result
+	}
+	return errors.Join(result, voice.Close(ctx))
 }
 
 type hardwareSpeaker struct {