layout: restructure into src/ tests/ android/ scripts/ tools/

- extension/src/{port,platform,codepage} -> src/; native_render -> src/host
  (+ dxt, shaders/); libgr2 -> src/gr2; extension/third_party -> third_party
- extension/tests -> tests/port, libgr2/tests -> tests/gr2
- android-native -> android (build.sh, push-client.sh moved in)
- script -> scripts; tools/40250 -> tools/server; oracle -> tools/granny-oracle;
  perf tools -> tools/perf
- all build trees under build/ (native, release, android, port-gate)
- xrender:: CMake aliases -> mt::; port-map ledger impl paths rewritten

No code changes. ctest 15/15, port_gate macos+android PASS, port_map check 0 errors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

third_party/cryptopp/dh2.h

@@ -0,0 +1,70 @@
+// dh2.h - originally written and placed in the public domain by Wei Dai
+
+/// \file dh2.h
+/// \brief Classes for Unified Diffie-Hellman key exchange
+/// \since Crypto++ 3.0
+
+#ifndef CRYPTOPP_DH2_H
+#define CRYPTOPP_DH2_H
+
+#include "cryptlib.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+/// \brief Unified Diffie-Hellman in GF(p)
+/// \details A Diffie-Hellman domain is a set of parameters that must be shared
+///   by two parties in a key agreement protocol, along with the algorithms
+///   for generating key pairs and deriving agreed values.
+/// \sa AuthenticatedKeyAgreementDomain, <a href="http://www.weidai.com/scan-mirror/ka.html#DH2">Unified Diffie-Hellman</a>
+/// \since Crypto++ 3.0
+class DH2 : public AuthenticatedKeyAgreementDomain
+{
+public:
+	virtual ~DH2() {}
+
+	/// \brief Construct a DH2
+	DH2(SimpleKeyAgreementDomain &domain)
+		: d1(domain), d2(domain) {}
+	/// \brief Construct a DH2
+	DH2(SimpleKeyAgreementDomain &staticDomain, SimpleKeyAgreementDomain &ephemeralDomain)
+		: d1(staticDomain), d2(ephemeralDomain) {}
+
+	CryptoParameters & AccessCryptoParameters() {return d1.AccessCryptoParameters();}
+
+	unsigned int AgreedValueLength() const
+		{return d1.AgreedValueLength() + d2.AgreedValueLength();}
+
+	unsigned int StaticPrivateKeyLength() const
+		{return d1.PrivateKeyLength();}
+	unsigned int StaticPublicKeyLength() const
+		{return d1.PublicKeyLength();}
+	void GenerateStaticPrivateKey(RandomNumberGenerator &rng, byte *privateKey) const
+		{d1.GeneratePrivateKey(rng, privateKey);}
+	void GenerateStaticPublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const
+		{d1.GeneratePublicKey(rng, privateKey, publicKey);}
+	void GenerateStaticKeyPair(RandomNumberGenerator &rng, byte *privateKey, byte *publicKey) const
+		{d1.GenerateKeyPair(rng, privateKey, publicKey);}
+
+	unsigned int EphemeralPrivateKeyLength() const
+		{return d2.PrivateKeyLength();}
+	unsigned int EphemeralPublicKeyLength() const
+		{return d2.PublicKeyLength();}
+	void GenerateEphemeralPrivateKey(RandomNumberGenerator &rng, byte *privateKey) const
+		{d2.GeneratePrivateKey(rng, privateKey);}
+	void GenerateEphemeralPublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const
+		{d2.GeneratePublicKey(rng, privateKey, publicKey);}
+	void GenerateEphemeralKeyPair(RandomNumberGenerator &rng, byte *privateKey, byte *publicKey) const
+		{d2.GenerateKeyPair(rng, privateKey, publicKey);}
+
+	bool Agree(byte *agreedValue,
+		const byte *staticPrivateKey, const byte *ephemeralPrivateKey,
+		const byte *staticOtherPublicKey, const byte *ephemeralOtherPublicKey,
+		bool validateStaticOtherPublicKey=true) const;
+
+protected:
+	SimpleKeyAgreementDomain &d1, &d2;
+};
+
+NAMESPACE_END
+
+#endif