Add testnet support for palladium electrumx server

Add PalladiumTestnet class with testnet-specific configurations including ports, address prefixes, and genesis hash. Update docker-compose.yml with clear network configuration comments and documentation in README.md explaining how to switch between mainnet and testnet.

electrumx-patch/coins_plm.py

@@ -17,6 +17,31 @@ class Palladium(Bitcoin):
     # === Genesis hash (Bitcoin mainnet) ===
     GENESIS_HASH = "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"
 
+    # === Default ports ===
+    RPC_PORT = 2332
+    PEER_DEFAULT_PORTS = {'t': '2333', 's': '52333'}
+
     # === Deserializer ===
     DESERIALIZER = lib_tx.DeserializerSegWit
 
+
+class PalladiumTestnet(Palladium):
+    NAME = "Palladium"
+    SHORTNAME = "tPLM"
+    NET = "testnet"
+
+    # === Testnet address prefixes ===
+    P2PKH_VERBYTE = bytes([0x7f])  # 127 decimal - addresses start with 't'
+    P2SH_VERBYTE  = bytes([0x73])  # 115 decimal
+    WIF_BYTE      = bytes([0xff])  # 255 decimal
+
+    # === Bech32 prefix for testnet ===
+    HRP = "tplm"
+
+    # === Genesis hash (Bitcoin testnet) ===
+    GENESIS_HASH = "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943"
+
+    # === Testnet ports ===
+    RPC_PORT = 12332
+    PEER_DEFAULT_PORTS = {'t': '12333', 's': '62333'}
+