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/dsa.cpp

@@ -0,0 +1,66 @@
+// dsa.cpp - originally written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+
+#ifndef CRYPTOPP_IMPORTS
+
+#include "dsa.h"
+#include "asn.h"
+#include "integer.h"
+#include "filters.h"
+#include "nbtheory.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+size_t DSAConvertSignatureFormat(byte *buffer, size_t bufferSize, DSASignatureFormat toFormat, const byte *signature, size_t signatureLen, DSASignatureFormat fromFormat)
+{
+	Integer r, s;
+	StringStore store(signature, signatureLen);
+	ArraySink sink(buffer, bufferSize);
+
+	switch (fromFormat)
+	{
+	case DSA_P1363:
+		r.Decode(store, signatureLen/2);
+		s.Decode(store, signatureLen/2);
+		break;
+	case DSA_DER:
+	{
+		BERSequenceDecoder seq(store);
+		r.BERDecode(seq);
+		s.BERDecode(seq);
+		seq.MessageEnd();
+		break;
+	}
+	case DSA_OPENPGP:
+		r.OpenPGPDecode(store);
+		s.OpenPGPDecode(store);
+		break;
+	}
+
+	switch (toFormat)
+	{
+	case DSA_P1363:
+		r.Encode(sink, bufferSize/2);
+		s.Encode(sink, bufferSize/2);
+		break;
+	case DSA_DER:
+	{
+		DERSequenceEncoder seq(sink);
+		r.DEREncode(seq);
+		s.DEREncode(seq);
+		seq.MessageEnd();
+		break;
+	}
+	case DSA_OPENPGP:
+		r.OpenPGPEncode(sink);
+		s.OpenPGPEncode(sink);
+		break;
+	}
+
+	return (size_t)sink.TotalPutLength();
+}
+
+NAMESPACE_END
+
+#endif