TUI now creates a NativeAgent with tool registry/executor and uses
agent.process() for message handling. Tool calls display status lines
showing tool name, args, and success/error result. Falls back to
direct model client when agent is not configured.
Add LlamaCppClient to imports and handle llamacpp provider in createModelRouter.
Pass localProviders and currentLocalProvider configuration to MinimalTui to enable
the /backend command to access alternate provider configs.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>