Enhanced Warden implementation with comprehensive documentation

Added MD5 hashing and extensive testing documentation for future attempts
at supporting strict Warden servers like Warmane.

Enhancements:
- Added MD5 hash support to Crypto class (OpenSSL-based)
- Tested 6 different module ACK response formats against Warmane
- Analyzed module packet structure (37 bytes: opcode + seed + trailing)
- Enhanced debug logging for plaintext and encrypted Warden data

Documentation:
- WARDEN_IMPLEMENTATION.md: Complete implementation guide with all attempts
- WARDEN_QUICK_REFERENCE.md: Quick troubleshooting and testing guide

Test Results (Warmane):
- Empty ACK (0 bytes): Server silent
- XOR/MD5 checksum (18 bytes): Server silent
- Single byte (1 byte): Server disconnects (rejected)
- Echo trailing (20 bytes): Server silent
- Result + SHA1 (21 bytes): Server silent

Conclusion:
- Current implementation works with permissive/disabled Warden servers
- Warmane requires module execution or undocumented response format
- Full documentation provided for future reverse engineering attempts

Next steps documented:
1. Capture packets from real WoW client (protocol analysis)
2. Implement module execution engine (months of work)
3. Test with local AzerothCore server

include/auth/crypto.hpp

@@ -12,6 +12,12 @@ public:
     static std::vector<uint8_t> sha1(const std::vector<uint8_t>& data);
     static std::vector<uint8_t> sha1(const std::string& data);
 
+    /**
+     * MD5 hash (16 bytes)
+     */
+    static std::vector<uint8_t> md5(const std::vector<uint8_t>& data);
+    static std::vector<uint8_t> md5(const std::string& data);
+
     /**
      * HMAC-SHA1 message authentication code
      *