ShineLAN-X: Initiale Firmware + Hardware-Diagnose

- STM32F103RBT6 Firmware für Growatt ShineLAN-X
- Bitbang-SPI (EthernetENC) auf Port C (PC6/PC7/PC8/PC9)
- UART-Debug auf USART1 (PA9/PA10), Modbus temporär deaktiviert
- SO-Aktivitätstest und ESTAT-Register-Scan bestätigen:
  ENC28J60 läuft (SO aktiv), SI/MOSI-Verbindung unterbrochen
- Nächster Schritt: Pin 5 ENC28J60 nachlöten oder Bodge-Draht

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Growatt ShineLAN-X/firmware/lib/EthernetENC/src/Dns.h

@@ -0,0 +1,41 @@
+// Arduino DNS client for Enc28J60-based Ethernet shield
+// (c) Copyright 2009-2010 MCQN Ltd.
+// Released under Apache License, version 2.0
+
+#ifndef DNSClient_h
+#define DNSClient_h
+
+#include "EthernetUdp.h"
+
+class DNSClient
+{
+public:
+    // ctor
+    void begin(const IPAddress& aDNSServer);
+
+    /** Convert a numeric IP address string into a four-byte IP address.
+        @param aIPAddrString IP address to convert
+        @param aResult IPAddress structure to store the returned IP address
+        @result 1 if aIPAddrString was successfully converted to an IP address,
+                else error code
+    */
+    int inet_aton(const char *aIPAddrString, IPAddress& aResult);
+
+    /** Resolve the given hostname to an IP address.
+        @param aHostname Name to be resolved
+        @param aResult IPAddress structure to store the returned IP address
+        @result 1 if aIPAddrString was successfully converted to an IP address,
+                else error code
+    */
+    int getHostByName(const char* aHostname, IPAddress& aResult);
+
+protected:
+    uint16_t BuildRequest(const char* aName);
+    uint16_t ProcessResponse(uint16_t aTimeout, IPAddress& aAddress);
+
+    IPAddress iDNSServer;
+    uint16_t iRequestId;
+    EthernetUDP iUdp;
+};
+
+#endif