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.

packages/papi-utils/README.md

@@ -1 +1,12 @@
-# @polkadot-api/utils
+# @pezkuwi/papi-utils
+
+**Source:** `src/` is [`@polkadot-api/utils`](https://www.npmjs.com/package/@polkadot-api/utils/v/0.2.0) 0.2.0 from
+[polkadot-api](https://github.com/polkadot-api/polkadot-api) (MIT), with imports of
+`@polkadot-api/*` renamed to `@pezkuwi/*`. `dist/` is its build;
+`scripts/check-papi-sources.mjs` fails CI unless the source embedded in `dist/` equals `src/`.
+
+The upstream README follows.
+
+---
+
+## @polkadot-api/utils