Remove blocking CollectNow commands to fix heartbeat stability

Eliminates automatic CollectNow command sending on host connection which
was blocking the main message processing loop for up to 5 seconds per
command. Since agents transmit cached data every 2 seconds anyway, the
CollectNow optimization provided minimal benefit while causing heartbeat
detection issues. Also removes unused send_command wrapper method.

This should completely resolve intermittent host connection dropping.

dashboard/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cm-dashboard"
-version = "0.1.72"
+version = "0.1.73"
 edition = "2021"
 
 [dependencies]

dashboard/src/app.rs

@@ -134,12 +134,6 @@ impl Dashboard {
         })
     }
 
-    /// Send a command to a specific agent
-    pub async fn send_command(&mut self, hostname: &str, command: AgentCommand) -> Result<()> {
-        self.zmq_command_sender
-            .send_command(hostname, command)
-            .await
-    }
 
     pub async fn run(&mut self) -> Result<()> {
         info!("Starting dashboard main loop");
@@ -212,34 +206,18 @@ impl Dashboard {
                         metric_message.metrics.len()
                     );
 
-                    // Check if this is the first time we've seen this host
+                    // Track first contact with host (no command needed - agent sends data every 2s)
                     let is_new_host = !self
                         .initial_commands_sent
                         .contains(&metric_message.hostname);
 
                     if is_new_host {
                         info!(
-                            "First contact with host {}, sending initial CollectNow command",
+                            "First contact with host {} - data will update automatically",
                             metric_message.hostname
                         );
-
-                        // Send CollectNow command for immediate refresh
-                        if let Err(e) = self
-                            .send_command(&metric_message.hostname, AgentCommand::CollectNow)
-                            .await
-                        {
-                            error!(
-                                "Failed to send initial CollectNow command to {}: {}",
-                                metric_message.hostname, e
-                            );
-                        } else {
-                            info!(
-                                "✓ Sent initial CollectNow command to {}",
-                                metric_message.hostname
-                            );
-                            self.initial_commands_sent
-                                .insert(metric_message.hostname.clone());
-                        }
+                        self.initial_commands_sent
+                            .insert(metric_message.hostname.clone());
                     }
 
                     // Update metric store