Compliant rebrand: legal compliance, code audit, and documentation (Phases 0-3)

Phase 0 - Legal Compliance:
- COPYING: Add DragonX copyright, preserve all upstream attributions
- AUTHORS: Add DragonX developers section
- LICENSE: Restore standard FSF GPLv3 text (fix GNU→GENERAL error)
- Add DragonX copyright headers to all 21 modified source files
- contrib/debian/copyright: Add DragonX attribution
- README.md: Add GPLv3 Section 5(a) attribution section

Phase 1 - init.cpp Cleanup:
- PID file: hushd.pid → dragonxd.pid
- Shutdown thread: hush-shutoff → dragonx-shutoff
- Debug message: stopping HUSH → stopping DragonX

Phase 2 - HUSH3/ishush3 Code Audit:
- Rename ishush3 → isdragonx across ~15 source files
- Update "HUSH3" chain-identity checks to "DRAGONX" in consensus,
  difficulty, notarization, devtax, and RPC code
- Intentionally preserve cross-chain "HUSH3" refs (gateway, notary dest)
- Build verified: all three binaries compile cleanly

Phase 3 - Documentation:
- README.md: Full rewrite with DragonX chain params, build instructions
- Man pages: Create dragonxd.1, dragonx-cli.1, dragonx-tx.1 (v1.0.0)
- Doc files: Add beefy-DRAGONX.conf, dragonxd-systemd.md, dragonxd.service
- Init scripts: Create dragonxd.{conf,init,openrc,openrcconf,service}
- Debian packaging: Update control, changelog, install, manpages, examples
- Update doc/init.md and contrib/init/README.md

contrib/init/dragonxd.openrc

@@ -0,0 +1,87 @@
+#!/sbin/runscript
+
+# backward compatibility for existing gentoo layout 
+#
+if [ -d "/var/lib/hush/.hush" ]; then
+	HUSHD_DEFAULT_DATADIR="/var/lib/hush/.hush"
+else
+	HUSHD_DEFAULT_DATADIR="/var/lib/dragonxd"
+fi
+
+HUSHD_CONFIGFILE=${HUSHD_CONFIGFILE:-/etc/hush/hush.conf}
+HUSHD_PIDDIR=${HUSHD_PIDDIR:-/var/run/dragonxd}
+HUSHD_PIDFILE=${HUSHD_PIDFILE:-${HUSHD_PIDDIR}/dragonxd.pid}
+HUSHD_DATADIR=${HUSHD_DATADIR:-${HUSHD_DEFAULT_DATADIR}}
+HUSHD_USER=${HUSHD_USER:-${HUSH_USER:-hush}}
+HUSHD_GROUP=${HUSHD_GROUP:-hush}
+HUSHD_BIN=${HUSHD_BIN:-/usr/bin/dragonxd}
+HUSHD_NICE=${HUSHD_NICE:-${NICELEVEL:-0}}
+HUSHD_OPTS="${HUSHD_OPTS:-${HUSH_OPTS}}"
+
+name="Hush Full Node Daemon"
+description="Hush cryptocurrency P2P network daemon"
+
+command="/usr/bin/dragonxd"
+command_args="-pid=\"${HUSHD_PIDFILE}\" \
+		-conf=\"${HUSHD_CONFIGFILE}\" \
+		-datadir=\"${HUSHD_DATADIR}\" \
+		-daemon \
+		${HUSHD_OPTS}"
+
+required_files="${HUSHD_CONFIGFILE}"
+start_stop_daemon_args="-u ${HUSHD_USER} \
+			-N ${HUSHD_NICE} -w 2000"
+pidfile="${HUSHD_PIDFILE}"
+
+# The retry schedule to use when stopping the daemon. Could be either
+# a timeout in seconds or multiple signal/timeout pairs (like
+# "SIGKILL/180 SIGTERM/300")
+retry="${HUSHD_SIGTERM_TIMEOUT}"
+
+depend() {
+	need localmount net
+}
+
+# verify
+# 1) that the datadir exists and is writable (or create it)
+# 2) that a directory for the pid exists and is writable
+# 3) ownership and permissions on the config file
+start_pre() {
+	checkpath \
+	-d \
+	--mode 0750 \
+	--owner "${HUSHD_USER}:${HUSHD_GROUP}" \
+	"${HUSHD_DATADIR}"
+
+	checkpath \
+	-d \
+	--mode 0755 \
+	--owner "${HUSHD_USER}:${HUSHD_GROUP}" \
+	"${HUSHD_PIDDIR}"
+
+	checkpath -f \
+	-o ${HUSHD_USER}:${HUSHD_GROUP} \
+	-m 0660 \
+	${HUSHD_CONFIGFILE}
+
+	checkconfig || return 1
+}
+
+checkconfig()
+{
+	if ! grep -qs '^rpcpassword=' "${HUSHD_CONFIGFILE}" ; then
+		eerror ""
+		eerror "ERROR: You must set a secure rpcpassword to run dragonxd."
+		eerror "The setting must appear in ${HUSHD_CONFIGFILE}"
+		eerror ""
+		eerror "This password is security critical to securing wallets "
+		eerror "and must not be the same as the rpcuser setting."
+		eerror "You can generate a suitable random password using the following"
+		eerror "command from the shell:"
+		eerror ""
+		eerror "bash -c 'tr -dc a-zA-Z0-9 < /dev/urandom | head -c32 && echo'"
+		eerror ""
+		eerror ""
+		return 1
+	fi
+}