Initial commit: Pezkuwi SubQuery indexer

- pezkuwi.yaml: Relay chain staking indexer (rewards, slashes, pools, transfers, era info)
- pezkuwi-assethub.yaml: Asset Hub indexer (NominationPools, asset transfers)
- GraphQL schema for staking data entities
- Handler mappings from Nova SubQuery base

jest.config.ts

@@ -0,0 +1,4 @@
+export default {
+  preset: "ts-jest",
+  testMatch: ["**/tests/**/*.test.ts"],
+};