fix: keep tokio runtime available for compositor

src/main.rs

@@ -1,6 +1,15 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
 fn main() {
+    // libcosmic-yoda enables zbus' `tokio` feature, so zbus 5.14 expects an
+    // ambient Tokio runtime via Handle::current(). cosmic-comp's loop is not
+    // async, so hold a runtime guard for the lifetime of run().
+    let runtime = tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .expect("failed to build tokio runtime");
+    let _guard = runtime.enter();
+
     if let Err(err) = cosmic_comp::run(Default::default()) {
         tracing::error!("Error occured in main(): {}", err);
         std::process::exit(1);