Use build timestamp version in TUI display

The TUI agent state was using CARGO_PKG_VERSION (0.1.0) instead of
version::current_version() which returns the RFC 3339 build timestamp.

src/main.rs

@@ -246,7 +246,7 @@ async fn async_main() {
         let event_bus = tui::EventBus::new(100);
         let agent_state = Arc::new(Mutex::new(tui::AgentState::new(
             hostname,
-            env!("CARGO_PKG_VERSION").to_string(),
+            version::current_version().to_string(),
         )));
 
         // Spawn TUI task