Initial commit: snapshot of spesmilo/electrumx 2.0.0

Unmodified source tree of upstream commit 280cb339aa158e099eb936033eecd15719770651
("Merge pull request #389 from SomberNight/202607_release_2_0",
https://github.com/spesmilo/electrumx, release 2.0.0, 3 July 2026).

All Palladium-specific changes are in the commits that follow.

contrib/systemd/electrumx.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=Electrumx
+After=network.target
+
+[Service]
+EnvironmentFile=/etc/electrumx.conf
+ExecStart=/usr/local/bin/electrumx_server
+ExecStop=/usr/local/bin/electrumx_rpc -p 8000 stop
+User=electrumx
+LimitNOFILE=8192
+TimeoutStopSec=30min
+
+[Install]
+WantedBy=multi-user.target