Fix --acd flag not being passed to agent mode

The --acd flag was being checked AFTER the agent mode early return,
so it was never applied when running with --agent.

Fix: Pass acd_enabled parameter to run_agent_mode() and call
agent.set_acd_enabled(true) when the flag is set.

crates/g3-cli/src/lib.rs

@@ -93,6 +93,7 @@ pub async fn run() -> Result<()> {
             cli.chat,
             cli.include_prompt.clone(),
             cli.no_auto_memory,
+            cli.acd,
         )
         .await;
     }