Add Pezkuwi chain type definitions

Adds type definitions for Pezkuwi mainnet to enable proper extrinsic encoding.
- ExtrinsicSignature mapped to MultiSignature
- Address and LookupSource mapped to MultiAddress
- Type aliases for pezsp_runtime types

chains/types/pezkuwi.json

@@ -0,0 +1,12 @@
+{
+  "types": {
+    "ExtrinsicSignature": "MultiSignature",
+    "Address": "pezsp_runtime::multiaddress::MultiAddress",
+    "LookupSource": "pezsp_runtime::multiaddress::MultiAddress"
+  },
+  "typesAlias": {
+    "pezsp_runtime::multiaddress::MultiAddress": "MultiAddress",
+    "pezsp_runtime::MultiSignature": "MultiSignature",
+    "pezsp_runtime.generic.era.Era": "Era"
+  }
+}