[socket] Fix IPv6 compilation error on host platform (#14101)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

esphome/components/socket/socket.cpp

@@ -59,8 +59,14 @@ size_t format_sockaddr_to(const struct sockaddr *addr_ptr, socklen_t len, std::s
 #if USE_NETWORK_IPV6
   else if (addr_ptr->sa_family == AF_INET6 && len >= sizeof(sockaddr_in6)) {
     const auto *addr = reinterpret_cast<const struct sockaddr_in6 *>(addr_ptr);
-#ifndef USE_SOCKET_IMPL_LWIP_TCP
-    // Format IPv4-mapped IPv6 addresses as regular IPv4 (not supported on ESP8266 raw TCP)
+#ifdef USE_HOST
+    // Format IPv4-mapped IPv6 addresses as regular IPv4 (POSIX layout, no LWIP union)
+    if (IN6_IS_ADDR_V4MAPPED(&addr->sin6_addr) &&
+        esphome_inet_ntop4(&addr->sin6_addr.s6_addr[12], buf.data(), buf.size()) != nullptr) {
+      return strlen(buf.data());
+    }
+#elif !defined(USE_SOCKET_IMPL_LWIP_TCP)
+    // Format IPv4-mapped IPv6 addresses as regular IPv4 (LWIP layout)
     if (addr->sin6_addr.un.u32_addr[0] == 0 && addr->sin6_addr.un.u32_addr[1] == 0 &&
         addr->sin6_addr.un.u32_addr[2] == htonl(0xFFFF) &&
         esphome_inet_ntop4(&addr->sin6_addr.un.u32_addr[3], buf.data(), buf.size()) != nullptr) {

tests/components/socket/common.yaml

@@ -0,0 +1,11 @@
+substitutions:
+  network_enable_ipv6: "false"
+
+socket:
+
+wifi:
+  ssid: MySSID
+  password: password1
+
+network:
+  enable_ipv6: ${network_enable_ipv6}

tests/components/socket/test-ipv6.esp32-idf.yaml

@@ -0,0 +1,4 @@
+substitutions:
+  network_enable_ipv6: "true"
+
+<<: !include common.yaml

tests/components/socket/test-ipv6.host.yaml

@@ -0,0 +1,4 @@
+socket:
+
+network:
+  enable_ipv6: true

tests/components/socket/test.esp32-idf.yaml

@@ -0,0 +1 @@
+<<: !include common.yaml

tests/components/socket/test.host.yaml

@@ -0,0 +1,3 @@
+socket:
+
+network: