UR-Nexus 1.54.0

• Wired the 1.53.0 capability libraries into runnable commands. They were
  verified modules but nothing invoked them; these are the execution paths.
• Added /speak <text> (alias /say), which drives the platform speech
  synthesiser with --voice and --rate. Text is passed on stdin, so it is
  never shell-parsed, and a missing synthesiser reports an install hint rather
  than failing the session.
• Added /computer screenshot|click|type (alias /desktop-control). Clicks
  are validated against the real screen geometry and refuse to run when the
  geometry cannot be read, rather than clicking blind. Every state-changing
  action requires an explicit --yes; without it the command prints what it
  would do and stops. A macOS screenshot that silently writes nothing reports
  the Screen Recording permission requirement.
• Added /memory-suggest (alias /suggest-memory), which scans recent user
  messages from the live transcript and proposes durable facts with their
  type, confidence and originating rule. Proposals are never saved on their
  own; /remember still does the writing.