Add integration tests, README overhaul, and bug fixes

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug Report
+about: Report a bug in eth.zig
+title: ''
+labels: bug
+assignees: ''
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To reproduce**
+Steps to reproduce the behavior:
+1. Code snippet or minimal reproduction
+2. Expected output vs actual output
+
+**Expected behavior**
+What you expected to happen.
+
+**Environment**
+- Zig version: [e.g. 0.15.2]
+- OS: [e.g. Ubuntu 24.04, macOS 15]
+- eth.zig version: [e.g. 0.1.0]
+
+**Additional context**
+Any other context, stack traces, or error messages.

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature Request
+about: Suggest a new feature for eth.zig
+title: ''
+labels: enhancement
+assignees: ''
+---
+
+**What problem does this solve?**
+A clear description of the use case or pain point.
+
+**Proposed solution**
+How you think this could be implemented.
+
+**Alternatives considered**
+Any alternative solutions or workarounds you've considered.
+
+**Additional context**
+Any other context, references to EIPs, or examples from other libraries.

CHANGELOG.md

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+# Changelog
+
+All notable changes to eth.zig will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.1.0] - 2026-02-26
+
+Initial release of eth.zig -- a feature-complete, pure Zig Ethereum client library.
+
+### Added
+
+**Primitives**
+- `Address` (20 bytes), `Hash` (32 bytes), `Bytes32` types with hex conversions
+- EIP-55 checksummed address formatting
+- `u256` helpers: `fromBigEndianBytes`, `toBigEndianBytes`, `fromHex`, `toHex`
+- Hex encode/decode utilities
+
+**Encoding**
+- RLP encoding/decoding per Ethereum Yellow Paper (structs, tuples, slices, integers)
+- ABI encoding: all Solidity types (uint8..uint256, address, bool, bytes, string, arrays, tuples)
+- ABI decoding: typed decoding of return values and event data
+- Comptime ABI: compile-time function selector and event topic computation
+- JSON ABI parser: parse Solidity JSON ABI files into eth.zig types
+
+**Crypto**
+- Keccak-256 hashing (wraps `std.crypto.hash.sha3.Keccak256`)
+- secp256k1 ECDSA signing with recovery ID (RFC 6979, EIP-2 low-S)
+- Signature types with compact format support
+- EIP-155 replay protection
+
+**Transaction Types**
+- Legacy, EIP-2930, EIP-1559, EIP-4844 transaction types
+- Transaction serialization (unsigned and signed)
+- Receipt, block header, log, and access list types
+- EIP-4844 blob types and sidecar construction helpers
+
+**Accounts**
+- BIP-39 mnemonic generation and validation (2048-word English wordlist)
+- BIP-32/44 HD wallet key derivation
+- Private key signing: messages (EIP-191) and transactions
+
+**Transport**
+- HTTP JSON-RPC transport (`std.http.Client`)
+- WebSocket JSON-RPC transport with TLS support
+- Subscription management (newHeads, logs, newPendingTransactions)
+- JSON-RPC 2.0 request/response types with batch support
+
+**Client**
+- Provider: 24+ read-only RPC methods (getBalance, getBlock, call, estimateGas, getLogs, etc.)
+- Wallet: signing client with sendTransaction, waitForReceipt, auto nonce/gas
+- Contract: high-level read/write helpers with ABI encoding
+- Multicall3: batched contract calls in a single RPC round-trip
+- Event log decoding and filtering
+
+**Standards**
+- EIP-712 typed structured data hashing and signing
+- ENS resolution: forward (name -> address), reverse (address -> name), namehash
+- ERC-20 and ERC-721 contract interaction helpers
+
+**Chains**
+- Chain definitions: Ethereum, Arbitrum, Optimism, Base, Polygon (mainnet + testnets)
+- Includes Multicall3 addresses, ENS registries, block explorer URLs
+
+**Utilities**
+- Wei/Gwei/Ether unit conversions
+- Common constants (zero address, max uint256, etc.)

CONTRIBUTING.md

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+# Contributing to eth.zig
+
+Thanks for your interest in contributing to eth.zig! This document covers everything you need to get started.
+
+## Prerequisites
+
+- [Zig >= 0.15.2](https://ziglang.org/download/)
+- Git
+
+## Getting Started
+
+```bash
+git clone https://github.com/StrobeLabs/eth.zig.git
+cd eth.zig
+
+# Build
+zig build
+
+# Run tests
+zig build test
+
+# Check formatting
+zig fmt --check src/ tests/
+
+# Format code
+zig fmt src/ tests/
+```
+
+## Architecture
+
+eth.zig uses a layered architecture where each layer only depends on layers below it. This makes every layer independently testable.
+
+```
+Layer 1:  Primitives     (zero deps, no allocator needed)
+          primitives.zig, uint256.zig, hex.zig
+
+Layer 2:  Encoding       (-> primitives)
+          rlp.zig, abi_encode.zig, abi_decode.zig, abi_types.zig, abi_comptime.zig
+
+Layer 3:  Crypto         (-> primitives)
+          keccak.zig, secp256k1.zig, signature.zig
+
+Layer 4:  Types          (-> primitives, encoding, crypto)
+          transaction.zig, receipt.zig, block.zig, log.zig, access_list.zig, blob.zig
+
+Layer 5:  Signer         (-> crypto, types)
+          signer.zig, eip155.zig, hd_wallet.zig, mnemonic.zig
+
+Layer 6:  Transport      (-> types)
+          http_transport.zig, ws_transport.zig, json_rpc.zig, subscription.zig
+
+Layer 7:  Client         (-> transport, types, encoding)
+          provider.zig, wallet.zig
+
+Layer 8:  Contract       (-> client, encoding, signer)
+          contract.zig, event.zig, multicall.zig
+
+Layer 9:  Standards      (-> client, contract, crypto)
+          eip712.zig, ens/
+
+Layer 10: Chains         (pure data, zero deps)
+          chains/
+```
+
+Layers 1-3 have zero I/O. Layers 1-5 have zero network dependencies.
+
+## Pull Requests
+
+1. Fork the repo and create a branch from `main`
+2. Write your code -- follow existing patterns in the codebase
+3. Add tests for new functionality
+4. Run `zig fmt src/ tests/` to format your code
+5. Run `zig build test` to make sure all tests pass
+6. Open a PR against `main`
+
+## Code Style
+
+- Follow `zig fmt` formatting (enforced by CI)
+- Use descriptive variable names
+- Keep functions focused and small
+- Add doc comments (`///`) to public functions
+- Prefer comptime over runtime where possible -- this is a core design principle
+- No external dependencies -- everything builds on Zig's standard library
+
+## Reporting Issues
+
+- Use the bug report template for bugs
+- Use the feature request template for new features
+- Include Zig version, OS, and steps to reproduce
+
+## License
+
+By contributing, you agree that your contributions will be licensed under the MIT License.