fix(test): correct receiver loop count in MultipleSendersReceivers

Problem:
- Receivers were exiting after receiving only messages_per_sender (5) messages
- In broadcast mode, each message is sent to ALL receivers
- If sender1 completes quickly, all receivers get 5 messages and exit
- This causes sender2's messages to fail (no active receivers)

Solution:
- Each receiver should loop for num_senders * messages_per_sender (2 * 5 = 10) messages
- This ensures all receivers stay active until ALL senders complete
- Now receivers wait for: 2 senders × 5 messages each = 10 total messages
- Expected received_count: 2 senders × 5 messages × 2 receivers = 20 messages

This fix ensures all senders can successfully complete their sends before
any receiver exits.

test/test_ipc_channel.cpp

@@ -537,6 +537,7 @@ TEST_F(ChannelTest, MultipleSendersReceivers) {
   const int num_senders = 2;
   const int num_receivers = 2;
   const int messages_per_sender = 5;
+  const int total_messages = num_senders * messages_per_sender;  // Each receiver should get all messages
   
   std::atomic<int> sent_count{0};
   std::atomic<int> received_count{0};
@@ -550,7 +551,8 @@ TEST_F(ChannelTest, MultipleSendersReceivers) {
           channel ch(name.c_str(), receiver);
           receivers_ready.count_down();  // Signal this receiver is ready
           
-          for (int j = 0; j < messages_per_sender; ++j) {
+          // Each receiver should receive ALL messages from ALL senders (broadcast mode)
+          for (int j = 0; j < total_messages; ++j) {
               buffer buf = ch.recv(2000);
               if (!buf.empty()) {
                   ++received_count;