Finish std::shared_ptr -> Ref migration

src/connection.hpp

@@ -3,13 +3,13 @@
 #include <cassert>
 #include <cstring>
 #include <deque>
-#include <memory>
 #include <sys/socket.h>
 #include <sys/uio.h>
 #include <unistd.h>
 
 #include "arena.hpp"
 #include "connection_handler.hpp"
+#include "reference.hpp"
 
 #ifndef __has_feature
 #define __has_feature(x) 0
@@ -330,7 +330,8 @@ private:
    * @param server Reference to server associated with this connection
    */
   Connection(struct sockaddr_storage addr, int fd, int64_t id,
-             size_t epoll_index, ConnectionHandler *handler, Server &server);
+             size_t epoll_index, ConnectionHandler *handler,
+             WeakRef<Server> server);
 
   // Networking interface - only accessible by Server
   int readBytes(char *buf, size_t buffer_size);
@@ -347,7 +348,7 @@ private:
   struct sockaddr_storage addr_; // sockaddr_storage handles IPv4/IPv6
   Arena arena_;
   ConnectionHandler *handler_;
-  std::weak_ptr<Server> server_; // Weak reference to server for safe cleanup
+  WeakRef<Server> server_; // Weak reference to server for safe cleanup
 
   std::deque<std::string_view, ArenaStlAllocator<std::string_view>> messages_{
       ArenaStlAllocator<std::string_view>{&arena_}};