M1: Ethernet bring-up

net_eth module brings up the Waveshare ESP32-P4-ETH-POE Ethernet
interface (internal EMAC + IP101GRI PHY) and waits for a DHCP lease.

Pin map confirmed via Waveshare wiki + ESPHome's working config:
  MDC=31, MDIO=52, REF_CLK=50 (CLK_EXT_IN from PHY)
  TX_EN=49, TXD0=34, TXD1=35
  CRS_DV=28, RXD0=30, RXD1=29
  PHY reset/enable=51, PHY addr=1

app_main initializes NVS, netif, the default event loop, then starts
the Ethernet driver and waits up to 30s for an IP. On success it logs
the IP; on timeout it logs a warning and proceeds (the driver keeps
retrying in the background).

sdkconfig: declare 16 MB flash so partitions.csv (6.1 MB) fits.
main/CMakeLists.txt: explicit REQUIRES esp_eth esp_event esp_netif
nvs_flash.

Acceptance (per M1 in the impl guide): device gets a DHCP lease over
Ethernet and prints its IP. Build is clean against ESP-IDF 5.4 for
target esp32p4.

1 files changed, 21 insertions, 10 deletions

diff --git a/main/app_main.c b/main/app_main.c
index 3c30497..8b91537 100644
--- a/main/app_main.c
+++ b/main/app_main.c
@@ -1,7 +1,9 @@
-#include <esp_log.h>
-#include <esp_event.h>
-#include <esp_netif.h>
-#include <nvs_flash.h>
+#include "net_eth.h"
+
+#include "esp_event.h"
+#include "esp_log.h"
+#include "esp_netif.h"
+#include "nvs_flash.h"
 
 static const char *TAG = "viewport";
 
@@ -13,10 +15,19 @@ void app_main(void)
 
     ESP_LOGI(TAG, "Scrypted Viewport boot");
 
-    // TODO: Ethernet (ESP32-P4 EMAC + Waveshare PoE PHY)
-    // TODO: mDNS _scrypted-viewport._tcp.local
-    // TODO: HTTP server: /state /config /frame
-    // TODO: MIPI-DSI panel init (800x480 IPS, default portrait 480x800)
-    // TODO: JPEG decode -> framebuffer
-    // TODO: Capacitive touch -> outbound /state POST
+    ESP_ERROR_CHECK(net_eth_init());
+    if (net_eth_wait_for_ip(30 * 1000) == ESP_OK) {
+        ESP_LOGI(TAG, "online at %s", net_eth_get_ip_str());
+    } else {
+        ESP_LOGW(TAG, "no DHCP lease after 30s, will keep retrying in the background");
+    }
+
+    // TODO M2: mDNS _scrypted-viewport._tcp.local
+    // TODO M2: HTTP server: GET /state
+    // TODO M3: MIPI-DSI panel init (800x480 IPS, default portrait 480x800)
+    // TODO M4: /config persistence (NVS)
+    // TODO M5: /frame JPEG decode -> framebuffer
+    // TODO M6: /state POST + idle timer
+    // TODO M7: Capacitive touch -> outbound /state POST
+    // TODO M8: Local screens (IP, loading) + BOOT button
 }