fix(test): fix broken import path

chore(repo): rename import paths

chore(repo): rename package to match new owner

fix(response): error handling when status == 0

Return a more comprehensive error when the type of reponse in the
envelope is mismatched (when status != 1)

chore(repo): update README

refactor(client): reorg structure & error handling

BREAKING CHANGES:
- Move all client-related code to pkg/client directory
- Rename test files to follow Go conventions (*_integration_test.go)
- Replace custom noError helper with testify/assert
- Update response types and error handling in client methods
- Move types to internal/types package

Features:
- Add StatusResponse type for transaction receipt status
- Add url.Values based parameter handling
- Improve test organization with integration test build tags

The changes improve the overall package structure and maintainability
while providing better error handling and type safety. Client code is now
better organized in its own package with clearer separation of concerns.

feat: add EtherscanTx interface

fix: remove all unused fields from erc1155 to remove complexity

fix: go back to using BigInt. Return zero for empty string

fix: remove import. replace uint8 with int