Remove refresh functionality that causes dashboard to hang

- Remove 'r' key handler that was causing hang on refresh
- Remove RefreshRequested event and check_refresh_request method
- Remove send_refresh_commands function and ZMQ command protocol
- Remove refresh_requested field from App struct
- Clean up status line text (refresh -> tick)

The refresh functionality was causing the dashboard to become unresponsive
when pressing 'r' key. This removes all refresh-related code to fix the issue.

dashboard/src/main.rs

@@ -53,7 +53,7 @@ struct Cli {
     #[arg(short = 'H', long, value_name = "HOST")]
     host: Option<String>,
 
-    /// Interval (ms) to refresh dashboard when idle
+    /// Interval (ms) for dashboard tick rate
     #[arg(long, default_value_t = 250)]
     tick_rate: u64,
 
@@ -154,10 +154,6 @@ fn run_app(
     while !app.should_quit() {
         drain_app_events(app, event_rx);
         
-        // Check for refresh requests
-        if app.check_refresh_request() {
-            send_refresh_commands(app)?;
-        }
         
         terminal.draw(|frame| ui::render(frame, app))?;
 
@@ -307,57 +303,6 @@ fn metrics_blocking_loop(
     Ok(())
 }
 
-fn send_refresh_commands(app: &mut App) -> Result<()> {
-    let endpoints = app.zmq_endpoints();
-    if endpoints.is_empty() {
-        return Ok(());
-    }
-    
-    let zmq_context = NativeZmqContext::new();
-    
-    for endpoint in endpoints {
-        // Convert metrics endpoint (6130) to command endpoint (6131)
-        let command_endpoint = endpoint.replace(":6130", ":6131");
-        
-        let socket = zmq_context.socket(zmq::REQ)?;
-        socket.set_linger(0)?;
-        socket.set_rcvtimeo(5000)?; // 5 second timeout
-        socket.set_sndtimeo(5000)?; // 5 second timeout
-        
-        match socket.connect(&command_endpoint) {
-            Ok(()) => {
-                debug!("Sending refresh command to {}", command_endpoint);
-                
-                match socket.send("refresh", 0) {
-                    Ok(()) => {
-                        // Wait for response
-                        match socket.recv_string(0) {
-                            Ok(Ok(response)) => {
-                                debug!("Refresh response from {}: {}", command_endpoint, response);
-                                // Update status via public method would be needed, for now just log
-                                debug!("Refresh sent to agents - response: {}", response);
-                            }
-                            Ok(Err(e)) => {
-                                warn!("String conversion error from {}: {:?}", command_endpoint, e);
-                            }
-                            Err(e) => {
-                                warn!("No response from {}: {}", command_endpoint, e);
-                            }
-                        }
-                    }
-                    Err(e) => {
-                        warn!("Failed to send refresh to {}: {}", command_endpoint, e);
-                    }
-                }
-            }
-            Err(e) => {
-                warn!("Failed to connect to command endpoint {}: {}", command_endpoint, e);
-            }
-        }
-    }
-    
-    Ok(())
-}
 
 fn handle_zmq_message(
     message: &NativeZmqMessage,