docs: explain backpressure rationale for PTY event channel in

src/terminal.rs

@@ -104,7 +104,10 @@ pub struct EventProxy(
 
 impl EventListener for EventProxy {
     fn send_event(&self, event: Event) {
-        //TODO: handle error
+        // Bounded channel; blocking_send propagates backpressure to alacritty's
+        // PTY reader instead of letting events accumulate. Called from alacritty's
+        // std::thread PTY reader (not a tokio worker), so blocking is safe and
+        // blocking_send won't panic.
         let _ = self.2.blocking_send((self.0, self.1, event));
     }
 }