socket_proxy.cpp: Add Mutex & Flush for Socket Protection

Signed-off-by: Collecting <collecting@noreply.localhost>

src/core/internal_network/socket_proxy.cpp

@@ -307,9 +307,15 @@ std::pair<s32, Errno> ProxySocket::SendTo(u32 flags, std::span<const u8> message
 }
 
 Errno ProxySocket::Close() {
+    std::lock_guard guard(packets_mutex);
     fd = INVALID_SOCKET;
     closed = true;
 
+    // Flush any pending packets so they don't get processed after closure
+    while (!received_packets.empty()) {
+        received_packets.pop();
+    }
+
     return Errno::SUCCESS;
 }