Link support codes to agent sessions

- Server: Accept support_code param in WebSocket connection
- Server: Link code to session when agent connects, mark as connected
- Server: Mark code as completed when agent disconnects
- Agent: Accept support code from command line argument
- Agent: Send hostname and support_code in WebSocket params
- Portal: Trigger agent download with code in filename
- Portal: Show code reminder in download instructions
- Dashboard: Add machines list fetching (Access tab)
- Add TODO.md for feature tracking

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

agent/src/transport/websocket.rs

@@ -29,15 +29,35 @@ pub struct WebSocketTransport {
 
 impl WebSocketTransport {
     /// Connect to the server
-    pub async fn connect(url: &str, agent_id: &str, api_key: &str) -> Result<Self> {
-        // Append agent_id and API key as query parameters
+    pub async fn connect(
+        url: &str,
+        agent_id: &str,
+        api_key: &str,
+        hostname: Option<&str>,
+        support_code: Option<&str>,
+    ) -> Result<Self> {
+        // Build query parameters
+        let mut params = format!("agent_id={}&api_key={}", agent_id, api_key);
+
+        if let Some(hostname) = hostname {
+            params.push_str(&format!("&hostname={}", urlencoding::encode(hostname)));
+        }
+
+        if let Some(code) = support_code {
+            params.push_str(&format!("&support_code={}", code));
+        }
+
+        // Append parameters to URL
         let url_with_params = if url.contains('?') {
-            format!("{}&agent_id={}&api_key={}", url, agent_id, api_key)
+            format!("{}&{}", url, params)
         } else {
-            format!("{}?agent_id={}&api_key={}", url, agent_id, api_key)
+            format!("{}?{}", url, params)
         };
 
         tracing::info!("Connecting to {} as agent {}", url, agent_id);
+        if let Some(code) = support_code {
+            tracing::info!("Using support code: {}", code);
+        }
 
         let (ws_stream, response) = connect_async(&url_with_params)
             .await