[socket] Implement working ready() for LWIP raw TCP sockets (ESP8266/RP2040)

Previously ready() always returned true on ESP8266/RP2040, causing
every socket to be checked on every loop iteration even when no data
was available.

Override ready() in LWIPRawImpl to check rx_buf_/rx_closed_/pcb_ state,
and in LWIPRawListenImpl to check accepted_socket_count_. This uses
existing fields so no extra memory is needed per socket.

Keep ready() virtual only on the non-select path (ESP8266/RP2040) so
the select()-based path (ESP32) retains the non-virtual optimization
from the previous commit.

esphome/components/socket/lwip_raw_tcp_impl.cpp

@@ -452,6 +452,8 @@ class LWIPRawImpl : public Socket {
     errno = ENOSYS;
     return -1;
   }
+  bool ready() const override { return this->rx_buf_ != nullptr || this->rx_closed_ || this->pcb_ == nullptr; }
+
   int setblocking(bool blocking) final {
     if (pcb_ == nullptr) {
       errno = ECONNRESET;
@@ -576,6 +578,8 @@ class LWIPRawListenImpl final : public LWIPRawImpl {
     tcp_err(pcb_, LWIPRawImpl::s_err_fn);  // Use base class error handler
   }
 
+  bool ready() const override { return this->accepted_socket_count_ > 0; }
+
   std::unique_ptr<Socket> accept(struct sockaddr *addr, socklen_t *addrlen) override {
     if (pcb_ == nullptr) {
       errno = EBADF;

esphome/components/socket/socket.cpp

@@ -10,13 +10,9 @@ namespace esphome::socket {
 
 Socket::~Socket() {}
 
-bool Socket::ready() const {
 #ifdef USE_SOCKET_SELECT_SUPPORT
-  return !this->loop_monitored_ || App.is_socket_ready_(this->fd_);
-#else
-  return true;
+bool Socket::ready() const { return !this->loop_monitored_ || App.is_socket_ready_(this->fd_); }
 #endif
-}
 
 // Platform-specific inet_ntop wrappers
 #if defined(USE_SOCKET_IMPL_LWIP_TCP)

esphome/components/socket/socket.h

@@ -71,10 +71,14 @@ class Socket {
   int get_fd() const { return -1; }
 #endif
 
-  /// Check if socket has data ready to read (non-virtual for direct call)
-  /// For loop-monitored sockets, checks the Application's select() results
-  /// For non-monitored sockets, always returns true (assumes data may be available)
+  /// Check if socket has data ready to read
+  /// For select()-based sockets: non-virtual, checks Application's select() results
+  /// For LWIP raw TCP sockets: virtual, checks internal buffer state
+#ifdef USE_SOCKET_SELECT_SUPPORT
   bool ready() const;
+#else
+  virtual bool ready() const { return true; }
+#endif
 
  protected:
 #ifdef USE_SOCKET_SELECT_SUPPORT