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>

doc/dnsseed-policy.md

@@ -1,11 +1,11 @@
 # Expectations for DNS Seed operators
 
-Hush attempts to minimize the level of trust in DNS seeds,
+DragonX attempts to minimize the level of trust in DNS seeds,
 but DNS seeds still pose a small amount of risk for the network.
 As such, DNS seeds must be run by entities which have some minimum
-level of trust within the Hush community.
+level of trust within the DragonX community.
 
-Other implementations of Hush software may also use the same
+Other implementations of DragonX software may also use the same
 seeds and may be more exposed. In light of this exposure, this
 document establishes some basic expectations for operating DNS seeds.
 
@@ -15,7 +15,7 @@ and not sell or transfer control of the DNS seed. Any hosting services
 contracted by the operator are equally expected to uphold these expectations.
 
 1. The DNS seed results must consist exclusively of fairly selected and
-functioning Hush nodes from the public network to the best of the
+functioning DragonX nodes from the public network to the best of the
 operator's understanding and capability.
 
 2. For the avoidance of doubt, the results may be randomized but must not
@@ -25,7 +25,7 @@ urgent technical necessity and disclosed.
 3. The results may not be served with a DNS TTL of less than one minute.
 
 4. Any logging of DNS queries should be only that which is necessary
-for the operation of the service or urgent health of the Hush
+for the operation of the service or urgent health of the DragonX
 network and must not be retained longer than necessary nor disclosed
 to any third party.
 
@@ -41,13 +41,8 @@ details of their operating practices.
 related to the DNS seed operation.
 
 If these expectations cannot be satisfied the operator should discontinue
-providing services and contact the active Hush development team as well as
-creating an issue in the [Hush Git repository](https://git.hush.is./hush/hush3).
+providing services and contact the active DragonX development team as well as
+creating an issue in the [DragonX Git repository](https://git.dragonx.is/DragonX/dragonx).
 
 Behavior outside of these expectations may be reasonable in some
 situations but should be discussed in public in advance.
-
-See also
-----------
-- [hush-seeder](https://git.hush.is/hush/hush-seeder) is a reference
-  implementation of a DNS seed.