hygiene: Phase 4 — route unconditional debug output through LogPrint

Fourth phase of the code-hygiene remediation, addressing the ~1,082 stray
fprintf(stderr)/printf debug calls so consensus and hot paths stop spewing
to stderr/stdout. Done per-file (18 files) with conservative rules; the tree
builds clean, self-mines, and `verifychain` re-validates the whole chain
(pow/txdb/coins/miner paths) with -debug=1 enabling every converted line —
zero tinyformat/format-arg exceptions.

Net across 18 files: 174 commented-out debug lines deleted, 173 unconditional
live prints converted to LogPrint("<cat>",...)/LogPrintf (net/mining/pow/nspv/
zrpc categories, format strings + args preserved exactly), 40 pure-noise or
sensitive prints deleted, and 194 calls DELIBERATELY LEFT (already behind
fDebug/fZdebug guards, or genuine startup/fatal-error output that must reach
the console before logging init).

Notable:
- Deleted sensitive success-path dumps (nSPV SIG_TXHASH + full tx input/
  output/change amounts; kvupdate privkey/pubkey hex) that were writing key
  and amount material straight to stderr/stdout.
- Removed the raw 32-byte target hex dumps in the zawy adaptive-PoW helpers
  and the legacy one-shot `if(height==340000)` HUSH artifact in pow.cpp.
- Converted per-tx relay + ban/banlist (net), per-setgenerate MININGTHREADS
  (rpc/mining), signrawtransaction TXPOW, and per-message nSPV traces.
- Left format/arg-mismatched lines untouched (flagged) to avoid introducing
  tinyformat runtime throws.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/rpc/mining.cpp

@@ -363,7 +363,7 @@ UniValue setgenerate(const UniValue& params, bool fHelp, const CPubKey& mypk)
     }
 
     HUSH_MININGTHREADS = (int32_t)nGenProcLimit;
-	fprintf(stderr,"%s:HUSH_MININGTHREADS=%d\n", __FUNCTION__, HUSH_MININGTHREADS);
+	LogPrint("mining","%s:HUSH_MININGTHREADS=%d\n", __FUNCTION__, HUSH_MININGTHREADS);
 
     mapArgs["-gen"]           = (fGenerate ? "1" : "0");
     mapArgs ["-genproclimit"] = itostr(HUSH_MININGTHREADS);
@@ -847,7 +847,6 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp, const CPubKey& myp
     result.push_back(Pair("bits", strprintf("%08x", pblock->nBits)));
     result.push_back(Pair("height", (int64_t)(pindexPrev->GetHeight()+1)));
 
-    //fprintf(stderr,"return complete template\n");
     return result;
 }
 
@@ -898,7 +897,6 @@ UniValue submitblock(const UniValue& params, bool fHelp, const CPubKey& mypk)
         );
 
     CBlock block;
-    //LogPrintStr("Hex block submission: " + params[0].get_str());
     if (!DecodeHexBlk(block, params[0].get_str()))
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");
 
@@ -924,7 +922,6 @@ UniValue submitblock(const UniValue& params, bool fHelp, const CPubKey& mypk)
     CValidationState state;
     submitblock_StateCatcher sc(block.GetHash());
     RegisterValidationInterface(&sc);
-    //printf("submitblock, height=%d, coinbase sequence: %d, scriptSig: %s\n", chainActive.LastTip()->GetHeight()+1, block.vtx[0].vin[0].nSequence, block.vtx[0].vin[0].scriptSig.ToString().c_str());
     bool fAccepted = ProcessNewBlock(1,chainActive.LastTip()->GetHeight()+1,state, NULL, &block, true, NULL);
     UnregisterValidationInterface(&sc);
     if (fBlockPresent)