docs: rebrand documentation, packaging, and helper scripts to DragonX

The docs/packaging were largely un-rebranded Hush3 content, with several
docs stating facts that are wrong for DragonX. This rewrites them against
the verified DragonX source state.

Corrections (not just branding):
- PoW: RandomX (CPU), not Equihash/ASIC — README, overview.md, randomx.md
- Privacy: private from genesis (ac_private=1, Sapling@height1), not "as of
  block 340000" — overview.md, payment-api.md
- Removed the false "coinbase must be shielded" consensus claim
  (shield-coinbase.md, payment-api.md); coinbase is directly spendable
- Fixed default fee 0.0001 (was 0.0010000, 10x); stratum port 22769 (was 19031)
- datadir ~/.hush/DRAGONX, DRAGONX.conf, dragonxd/dragonx-cli/dragonx-tx,
  git.dragonx.is throughout; branch model dev->dragonx
- Softened the inherited dPoW reorg claim (no live DragonX notary infra)

Packaging: fix build-debian-package.sh + gen-manpages.sh to use the dragonx
binaries/manpages; rename bash-completions to dragonx*; drop hush-arrakis-chain
from the package. Keep /usr/share/hush (hardcoded in the binary for params).

Also: README links/logo, ObsidianDragon + SilentDragonXAndroid wallets,
networking/init/dev-process/contrib/util rebrand, and leftover helper scripts.
Delete legacy duplicates (hushd.* init/service, HUSH3.conf examples,
OLD_WALLETS.md, hsc.md) and rename hush-uri.bat -> dragonx-uri.bat.

Out of scope (noted, not changed): historical changelog/copyright, the Hush
mainnet airdrop snapshot, seed data files, depends/ source mirrors, and the
in-code strCurrencyUnits="HUSH".

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

contrib/init/dragonxd.openrc

@@ -8,7 +8,7 @@ else
 	HUSHD_DEFAULT_DATADIR="/var/lib/dragonxd"
 fi
 
-HUSHD_CONFIGFILE=${HUSHD_CONFIGFILE:-/etc/hush/hush.conf}
+HUSHD_CONFIGFILE=${HUSHD_CONFIGFILE:-/etc/dragonx/DRAGONX.conf}
 HUSHD_PIDDIR=${HUSHD_PIDDIR:-/var/run/dragonxd}
 HUSHD_PIDFILE=${HUSHD_PIDFILE:-${HUSHD_PIDDIR}/dragonxd.pid}
 HUSHD_DATADIR=${HUSHD_DATADIR:-${HUSHD_DEFAULT_DATADIR}}
@@ -18,8 +18,8 @@ HUSHD_BIN=${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"
+name="DragonX Full Node Daemon"
+description="DragonX cryptocurrency P2P network daemon"
 
 command="/usr/bin/dragonxd"
 command_args="-pid=\"${HUSHD_PIDFILE}\" \