add --no-agents flag to disable background agents

Disables memory scoring, surface, and observe agents when set.
Useful for testing with external backends (e.g. OpenRouter) where
background agent traffic would be slow and unnecessary.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

src/user/mod.rs

@@ -693,6 +693,10 @@ pub struct CliArgs {
     #[arg(long)]
     pub dmn_max_turns: Option<u32>,
 
+    /// Disable background agents (surface, observe, scoring)
+    #[arg(long)]
+    pub no_agents: bool,
+
     #[command(subcommand)]
     pub command: Option<SubCmd>,
 }