Function run_repl 

pub fn run_repl(
    manifest: &AgentManifest,
    driver: &dyn LlmDriver,
    tools: &ToolRegistry,
    memory: &dyn MemorySubstrate,
    max_turns: u32,
    budget_usd: f64,
    resume_id: Option<&str>,
) -> Result<()>

Run the interactive REPL.

This is the main entry point for apr code interactive mode. Returns when the user types /quit or Ctrl+D.

If resume_id is provided, loads conversation history from the corresponding session in ~/.apr/sessions/.