feat(settings): add streaming auto-follow toggle

New Streaming section on the Chat settings page with a checkbox that
controls whether the viewport follows new content while a response
streams. Default stays on. With it off, the anchored user message still
parks at the top on send, but no glide or end-follow correction runs and
the list's maintain-scroll-at-end stays disabled; the scroll-to-bottom
pill and session open keep scrolling explicitly.

Persisted through desktop settings like the other chat toggles (auto-save
diff, authoritative apply, sanitize), registered in settings search, and
localized in every locale.

packages/ui/src/lib/i18n/messages/es.settings.ts

@@ -1906,6 +1906,10 @@ export const settingsDict = {
   "settings.openchamber.visual.section.showToolsOpenedByDefault": "Mostrar herramientas abiertas por defecto",
   "settings.openchamber.visual.section.sessionAssistance": "Asistencia de sesión",
   "settings.openchamber.visual.section.reasoning": "Razonamiento",
+  "settings.openchamber.visual.section.streaming": "Streaming",
+  "settings.openchamber.visual.field.streamingAutoFollow": "Seguir el contenido nuevo durante el streaming",
+  "settings.openchamber.visual.field.streamingAutoFollowAria": "Seguir automáticamente el contenido nuevo mientras se transmite una respuesta",
+  "settings.openchamber.visual.field.streamingAutoFollowInfo": "Mientras llega una respuesta, la vista se desplaza hacia el contenido más reciente. Desactívalo para mantener la vista quieta y desplazarte manualmente.",
   "settings.openchamber.visual.section.messageAppearance": "Apariencia de los mensajes",
   "settings.openchamber.visual.section.toolsAndFiles": "Herramientas y archivos",
   "settings.openchamber.visual.section.composer": "Compositor",