Test DHCP-renewal wedge hypothesis: fully static IP on 2.12 pair

The wedge metronome (~300s: 297/297/322/437s across bus widths,
clocks, and power modes) matches FRITZ DHCP T1 renewal at half of a
10-min lease. Every wedging build ran an active dhcp client. Static
addressing removes the renewal TX path entirely; if the metronome
dies, root cause #2 is the DHCP renew packet through hosted's write
path. (2.9.7 experiment abandoned: slave image bootloops/rolls back
on this C6; version matrix documented for upstream.)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

firmware/main/net.c

@@ -21,14 +21,14 @@ static volatile bool s_got_ip;
 static void start_ping_diag(void);
 static void ping_diag_task(void *arg);
 
-/* Router DHCP has been observed to go silent for this MAC (flap throttling).
- * After 15 s without a lease, claim the previously granted address statically. */
+/* Fully static addressing: every observed SDIO wedge (~300 s uptime) coincides
+ * with the DHCP T1 renewal window, so the DHCP client stays out of the picture. */
 static void static_ip_fallback(void *arg)
 {
     (void)arg;
-    vTaskDelay(pdMS_TO_TICKS(15000));
+    vTaskDelay(pdMS_TO_TICKS(1000));
     if (!s_got_ip) {
-        ESP_LOGW(TAG, "no DHCP lease after 15s — falling back to static 192.168.86.53");
+        ESP_LOGI(TAG, "static addressing: 192.168.86.53 (DHCP client disabled)");
         esp_netif_dhcpc_stop(s_netif);
         esp_netif_ip_info_t ip = { 0 };
         ip.ip.addr = esp_ip4addr_aton("192.168.86.53");