Export and display Remote Braille through the reader

A controlled reader renders accepted application frames in a new
virtual-only cthulhu-braille mode at the controller's width and applies
its pan and route gestures; reader UI, flashes and secure frames are
never exported, and hidden frames are unroutable. A controller reader
reports its display width, shows peer cells as an untranslated raw
frame and forwards local pan and routing keys. The physical helper now
reports its width and edge pans.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/app/tentacles.go

@@ -39,6 +39,7 @@ type tentacleRuntime struct {
 	remoteInput        *remoteinput.Supervisor // Retained for the reader lifetime.
 	remoteInputHelper  string                  // Private fixture seam; production uses the reader's directory.
 	remoteInputChecked bool
+	virtualBraille     func() (virtualBraille, error) // Private fixture seam.
 	readerSettings     *preferencesWorker
 	extensionChanges   chan struct{}
 	forms              tentacleForms
@@ -191,10 +192,11 @@ func (runtime *tentacleRuntime) run(ctx context.Context) error {
 			speechDone := runtime.start_remote_speech(ctx, session)
 			keysDone := runtime.start_remote_keyboard(ctx, session)
 			captureDone := runtime.start_remote_capture(ctx, session)
+			brailleDone := runtime.start_remote_braille(ctx, session)
 			watchers.Add(1)
 			go func() {
 				defer watchers.Done()
-				defer func() { <-speechDone; <-keysDone; <-captureDone }()
+				defer func() { <-speechDone; <-keysDone; <-captureDone; <-brailleDone }()
 				select {
 				case <-session.Revoked():
 				case <-ctx.Done():