Prepares the move to Arduino 3.x / ESP-IDF 5.5, which renumbers
eth_phy_type_t (ETH_PHY_GENERIC is now 0) and only has the RMII MAC
API on the original ESP32.
- Store the PHY chip as our own id (eth_phy_id_t, the 2.x values) and
translate it by name at ETH.begin(), so NVS, backups and the web UI
keep their numbers on either framework.
- Build Ethernet only where CONFIG_ETH_USE_ESP32_EMAC is set instead of
everywhere but the C6. C3 and S3 could never use it. A stored
Ethernet connection falls back to Wi-Fi on those chips.
- /networksettings reports hasEthernet; the UI hides the Ethernet
options without it.
- Fix the UI PHY list: 5 is the KSZ8041, add the KSZ8081 (6), drop the
DM9051, an SPI chip the MAC can't drive.
- SSDP takes its address from WiFi/ETH.localIP() instead of the
tcpip_adapter API IDF 5 removed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
