[AngelCastilloB]

Description

Add README examples for direct reward-account transfers, independently signed sub-transaction batching, account balance constraints, Plutus V4 guards and native guard scripts. The examples use JavaScript objects and bigint amounts, and release builders after use.

Executing the transfer example exposed a withdrawal marshaling bug: the Bech32 string-address path passed a bigint into a WASM function expecting separate low/high words. Fix that call for both builders and add four regression cases covering ordinary and greater-than-32-bit amounts. The README uses the RewardAddress object form so its examples also work with the published 2.0.0-rc.1 package; the string-address fix is unreleased.

Validation:

• All six snippets type-check against the published RC declarations and execute against its actual npm artifact with local protocol-12 fixtures.
• The four regression cases fail against the published artifact and pass after the fix.
• Full build and suite: 58 suites, 718 tests passed.
• Source ESLint has no errors. Test-file lint retains the existing one-var error in the DRep test, outside the changed lines.
• No live network transactions were submitted.

Checklist

• I have added tests
• I have updated the documentation
• I have updated the CHANGELOG
• Are there any breaking changes? No.