Regtest coin: SHORTNAME RPLM instead of the inherited TPLM

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/electrumx/lib/coins.py

@@ -323,6 +323,7 @@ class PalladiumTestnet(Palladium):
 
 
 class PalladiumRegtest(PalladiumTestnet):
+    SHORTNAME = "RPLM"
     NET = "regtest"
     BECH32_HRP = "rplm"
     # same genesis block as Bitcoin regtest

tests/lib/test_palladium.py

@@ -30,6 +30,11 @@ def test_chain_params(coin, net, rpc_port, p2pkh, p2sh, genesis):
     assert coin.DESERIALIZER is lib_tx.DeserializerSegWit
 
 
+@pytest.mark.parametrize("coin,shortname", [(Palladium, "PLM"), (PalladiumTestnet, "TPLM"), (PalladiumRegtest, "RPLM")])
+def test_shortname(coin, shortname):
+    assert coin.SHORTNAME == shortname
+
+
 @pytest.mark.parametrize("coin,net", [(c, n) for c, n, *_ in PARAMS])
 def test_lookup_coin_class(coin, net):
     assert Coin.lookup_coin_class("Palladium", net) is coin