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/braille/braille.go

@@ -36,6 +36,9 @@ type Frame struct {
 	WordWrap       bool   `json:"wordWrap,omitempty"`
 	Dots           []byte `json:"dots,omitempty"`
 	// Routing metadata stays in the parent, never in the helper protocol.
+	// Raw marks final cells from a Remote peer as Unicode Braille runes; the
+	// parent sends them without contraction or word wrap.
+	Raw      bool           `json:"-"`
 	Routes   []TextRoute    `json:"-"`
 	Virtual  *VirtualRoute  `json:"-"`
 	Document *DocumentRoute `json:"-"`
@@ -62,9 +65,12 @@ type TextRoute struct {
 	BusName, Path, SourceText           string
 }
 
+// RoutingEvent reports a routing key, or, with Pan set to "left" or "right"
+// and Offset -1, a pan key that could not move the local viewport.
 type RoutingEvent struct {
 	ID     uint64 `json:"id"`
 	Offset int    `json:"offset"`
+	Pan    string `json:"pan,omitempty"`
 }
 
 const (