Fix sapling pool persistence and add subsidy/fees to getblock RPC

Lower SPROUT_VALUE_VERSION and SAPLING_VALUE_VERSION constants in
chain.h from upstream Zcash values (1001400/1010100) to 1000000.
When DragonX was rebranded from HUSH3, CLIENT_VERSION was reset from
3.10.5 to 1.0.0, falling below these thresholds. This caused
nSaplingValue to silently skip serialization, so the sapling pool
total reset to 0 on every node restart. Explorer nodes should reindex
once after upgrading.

Add subsidy and fees fields to the getblock RPC response so explorers
can display the correct 3 DRGX block reward separately from fees,
instead of showing the combined coinbase output as the reward.

src/chain.h

@@ -32,8 +32,12 @@ class CChainPower;
 #include <boost/foreach.hpp>
 
 extern bool fZindex;
-static const int SPROUT_VALUE_VERSION = 1001400;
+// These version thresholds control whether nSproutValue/nSaplingValue are
-static const int SAPLING_VALUE_VERSION = 1010100;
+// serialized in the block index. They must be <= CLIENT_VERSION or the
+// values will never be persisted, causing nChainSaplingValue to reset
+// to 0 after node restart. DragonX CLIENT_VERSION is 1000150 (v1.0.1.50).
+static const int SPROUT_VALUE_VERSION = 1000000;
+static const int SAPLING_VALUE_VERSION = 1000000;
 extern int32_t ASSETCHAINS_LWMAPOS;
 extern char SMART_CHAIN_SYMBOL[65];
 extern uint64_t ASSETCHAINS_NOTARY_PAY[];

src/rpc/blockchain.cpp

@@ -322,6 +322,15 @@ UniValue blockToJSON(const CBlock& block, const CBlockIndex* blockindex, bool tx
     result.push_back(Pair("anchor", blockindex->hashFinalSproutRoot.GetHex()));
     result.push_back(Pair("blocktype", "mined"));
 
+    // Report block subsidy and fees separately so explorers don't have to
+    // reimplement the reward schedule to display them.
+    CAmount nSubsidy = GetBlockSubsidy(blockindex->GetHeight(), Params().GetConsensus());
+    CAmount nCoinbase = block.vtx[0].GetValueOut();
+    CAmount nFees = nCoinbase - nSubsidy;
+    if (nFees < 0) nFees = 0; // block 1 has premine, avoid negative
+    result.push_back(Pair("subsidy", ValueFromAmount(nSubsidy)));
+    result.push_back(Pair("fees", ValueFromAmount(nFees)));
+
     UniValue valuePools(UniValue::VARR);
     valuePools.push_back(ValuePoolDesc("sapling", blockindex->nChainSaplingValue, blockindex->nSaplingValue));
     result.push_back(Pair("valuePools", valuePools));