Fix frozen client on ctrl+q: send bye instead of half-closing

Dropping the client's channel sender never closed the socket (the
server's reader thread keeps the connection open), so the client froze
waiting for frames. The server now sends a bye message; the client
exits cleanly on it and its socket close lets the server clean up.
Messages from already-disconnected clients are ignored. Verified
end-to-end with the real client in a PTY (exits 0, daemon survives).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main.rs

@@ -438,6 +438,11 @@ fn handle_ipc_event(
             all_clients.remove(&client_id);
         }
         IpcEvent::Message { client_id, msg } => {
+            // Ignorera meddelanden från klienter som redan kopplats ner
+            // (t.ex. efter bye) men vars socket ännu inte hunnit stängas.
+            if !all_clients.contains_key(&client_id) {
+                return;
+            }
             match msg {
                 ClientMessage::Input { data } => {
                     let bytes = ipc::from_hex(&data);
@@ -540,7 +545,12 @@ fn disconnect_instead_of_quit(
 ) {
     if app.should_quit {
         app.should_quit = false;
-        // Sändaren droppas → klientens ström stängs → klienten avslutar.
+        // Skicka bye så klienten avslutar och stänger socketen — att bara
+        // droppa sändaren räcker inte, eftersom serverns läsartråd håller
+        // anslutningen öppen och klienten annars fryser i väntan på frames.
+        if let Some((_, _, _, tx)) = all_clients.get(&client_id) {
+            let _ = tx.try_send(ServerMessage::Bye);
+        }
         all_clients.remove(&client_id);
     }
 }