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/dragonx-uri.bat

@@ -0,0 +1,46 @@
+@Echo On
+Title Reg Converter v1.1 & Color 1A
+REM ~ call :IsAdmin
+
+call :RegExport
+Exit
+
+:RegExport
+Set RegFile="%Temp%\~etsaclu.tmp"
+
+Set "dragonx=%~dp0"
+set "dragonx=%dragonx:\=\\%"
+
+If Exist %RegFile% (
+ Attrib -R -S -H %RegFile% &  Del /F /Q %RegFile%
+ If Exist %RegFile% cls & Echo Could not delete file %RegFile% & Pause
+)
+> %RegFile% Echo Windows Registry Editor Version 5.00
+>> %RegFile% Echo.
+>> %RegFile% Echo [HKEY_CLASSES_ROOT\dragonx]
+>> %RegFile% Echo @="URL:dragonx protocol"
+>> %RegFile% Echo "URL Protocol"=""
+>> %RegFile% Echo.
+>> %RegFile% Echo [HKEY_CLASSES_ROOT\dragonx\DefaultIcon]
+>> %RegFile% Echo @="silentdragon.exe"
+>> %RegFile% Echo.
+>> %RegFile% Echo [HKEY_CLASSES_ROOT\dragonx\Shell]
+>> %RegFile% Echo.
+>> %RegFile% Echo [HKEY_CLASSES_ROOT\dragonx\Shell\Open]
+>> %RegFile% Echo.
+>> %RegFile% Echo [HKEY_CLASSES_ROOT\dragonx\Shell\Open\Command]
+>> %RegFile% Echo @="%dragonx%silentdragon.exe \"%%1\""
+
+Start /Wait %systemroot%\Regedit.exe /S %RegFile%
+Del %RegFile%
+goto:eof
+
+:IsAdmin
+Reg.exe query "HKU\S-1-5-19\Environment"
+If Not %ERRORLEVEL% EQU 0 (
+ Cls & Echo You must have administrator rights to continue ... 
+ Pause & Exit
+)
+Cls
+goto:eof
+