release: bump to v1.3.1

dev is 22 commits past the v1.3.0 tag and still stamped 1.3.0, so a
release built from it would be indistinguishable from v1.3.0 on the wire,
in getnetworkinfo and to the wallet's updater.

Bump REVISION, not MINOR: the delta is bug fixes and wallet performance.
It adds no subsystem, and the new RPC-visible options (-notecachewarmup,
-checknotecache) are debug-help only.

  configure.ac, src/clientversion.h  1.3.0 -> 1.3.1 (CLIENT_VERSION 1030150)
  doc/man/*.1                        version strings restamped
  contrib/debian/changelog           1.3.1 entry
  src/chain.h                        the CLIENT_VERSION comment

The man page content needs no regeneration: every option in
`dragonxd --help` at 3032eb786 is already in dragonxd.1, and the two new
options appear only in -help-debug.

No consensus change since v1.3.0, so PROTOCOL_VERSION and
MIN_PEER_PROTO_VERSION are unchanged.

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

src/chain.h

@@ -35,7 +35,7 @@ extern bool fZindex;
 // These version thresholds control whether nSproutValue/nSaplingValue are
 // 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 1030050 (v1.3.0.50).
+// to 0 after node restart. DragonX CLIENT_VERSION is 1030150 (v1.3.1.50).
 static const int SPROUT_VALUE_VERSION = 1000000;
 static const int SAPLING_VALUE_VERSION = 1000000;
 // Block-index records written at >= this version store nSaplingValue as a boost::optional

src/clientversion.h

@@ -30,7 +30,7 @@
 // Must be kept in sync with configure.ac , ugh!
 #define CLIENT_VERSION_MAJOR 1
 #define CLIENT_VERSION_MINOR 3
-#define CLIENT_VERSION_REVISION 0
+#define CLIENT_VERSION_REVISION 1
 #define CLIENT_VERSION_BUILD 50
 
 //! Set to true for release, false for prerelease or test build