chore(papi): commit the sources behind the four polkadot-api packages (#15)

* chore(papi): commit the sources behind the four polkadot-api packages

papi-utils, bizinikiwi-bindings, metadata-builders and merkleize-metadata
held only dist/ builds, and no repository held their source. Every
source map in dist/ embeds the TypeScript it was compiled from; that is
now committed as src/ (59 files), and it matches upstream polkadot-api
(MIT) exactly once @polkadot-api/* imports are renamed:

  papi-utils           @polkadot-api/utils 0.2.0
  bizinikiwi-bindings  @polkadot-api/substrate-bindings 0.16.6
  metadata-builders    @polkadot-api/metadata-builders 0.13.0-0.13.2
  merkleize-metadata   @polkadot-api/merkleize-metadata 1.1.21-1.1.23

scripts/check-papi-sources.mjs, run in the lint job, fails unless the
source embedded in dist/ is exactly the committed src/. tsconfig.json
excludes these src/ trees; ESLint already skipped the packages. Each
README now states the upstream package and version.

* chore(papi): keep the upstream sources in upstream-src/

The pezkuwi-dev build treats any package with a src/ directory as its
own: it requires our license header on every file and builds it. These
are upstream files that must stay byte-identical to the source embedded
in dist/, so they live in upstream-src/ instead, which neither the build
nor the root tsconfig picks up.

packages/merkleize-metadata/upstream-src/utils.ts

@@ -0,0 +1,15 @@
+import { type HexString } from "@pezkuwi/bizinikiwi-bindings"
+import { fromHex } from "@pezkuwi/papi-utils"
+
+export const toBytes = (input: Uint8Array | HexString) =>
+  typeof input === "string" ? fromHex(input) : input
+
+export const compactTypeRefs = {
+  null: "void" as const,
+  u8: "compactU8" as const,
+  u16: "compactU16" as const,
+  u32: "compactU32" as const,
+  u64: "compactU64" as const,
+  u128: "compactU128" as const,
+  u256: "compactU256" as const,
+}