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>

util/docker-entrypoint.sh

@@ -4,17 +4,16 @@
 # file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html
 
 #set -ex
-echo "...Checking HUSH3.conf"
+echo "...Checking DRAGONX.conf"
 
-# TODO: support legacy location?
-if [ ! -e "$HOME/.hush/HUSH3/HUSH3.conf" ]; then
-    mkdir -p $HOME/.hush/HUSH3
+if [ ! -e "$HOME/.hush/DRAGONX/DRAGONX.conf" ]; then
+    mkdir -p $HOME/.hush/DRAGONX
 
     DATE=$(date)
-    echo "...Creating HUSH3.conf"
-    cat <<EOF > $HOME/.hush/HUSH3.conf
+    echo "...Creating DRAGONX.conf"
+    cat <<EOF > $HOME/.hush/DRAGONX/DRAGONX.conf
 # Generated by docker-entrypoint.sh at $DATE
-rpcuser=hush
+rpcuser=dragonx
 rpcpassword=${rpcpassword:-`dd if=/dev/urandom bs=33 count=1 2>/dev/null | base64`}
 txindex=1
 bind=${listenip:-127.0.0.1}
@@ -25,7 +24,7 @@ zdebug=0
 zindex=0
 EOF
 
-    cat $HOME/.hush/HUSH3/HUSH3.conf
+    cat $HOME/.hush/DRAGONX/DRAGONX.conf
 fi
 
 if [ $# -gt 0 ]; then
@@ -36,6 +35,6 @@ else
     args=("-pubkey=${pubkey} -ac_name=${assetchain} -addnode=${seednode}")
 fi
 
-echo "Running: hushd ${args[@]}"
+echo "Running: dragonxd ${args[@]}"
 
-exec hushd ${args[@]}
+exec dragonxd ${args[@]}