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.

eslint.config.js

@@ -9,7 +9,8 @@ export default [
       // see the tsconfig.eslint.json for explanation
       'packages/api-augment/src/dicle/*.ts',
       'packages/api-augment/src/pezkuwi/*.ts',
-      // compiled packages without sources here; there is nothing to lint
+      // upstream polkadot-api packages (src/ + committed dist/), kept in upstream's style;
+      // scripts/check-papi-sources.mjs ties dist/ to src/
       'packages/bizinikiwi-bindings/**',
       'packages/merkleize-metadata/**',
       'packages/metadata-builders/**',