feat: Implement LayerZero WHBAR Cross-Chain Bridge with Comprehensive E2E Testing

[quiet-node]

PR Description

This PR implements a complete LayerZero-based bridge solution for WHBAR (Wrapped HBAR) transfers between Hedera and Sepoli. The implementation includes deployment scripts, comprehensive E2E testing, and detailed documentation.

Deployment Infrastructure

Introduces three core deployment scripts with environment-based configuration:

• WHBAR Contract: Wrapped HBAR deployment with deposit/withdrawal functionality
• ERC20 Mock: Configurable test token deployment for cross-chain testing
• OFT Adapter: LayerZero Omnichain Fungible Token Adapter for bidirectional transfers

All scripts support both Hedera and Sepolia networks with block explorer integration and comprehensive validation. Full documentation available in path-to-relay/hedera-crosschain-bridge/scripts/deployments/README.md.

End-to-End Testing

Delivers a comprehensive E2E test suite validating the complete WHBAR bridging flow:

• Autonomous Deployment: Dynamic contract deployment without pre-deployed address dependencies
• Bidirectional Bridge Testing: Full Hedera ↔ Sepolia transfer validation with LayerZero V2
• Balance Verification: Rigorous tracking ensuring 1:1 cross-chain parity
• HBAR-to-WHBAR Conversion: Native HBAR wrapping and token economics validation

Includes extensive logging, block explorer integration, and 30-minute execution timeout. Complete setup guide in path-to-relay/hedera-crosschain-bridge/test/bridging-e2e/whbar/README.md.

Key Achievements

• ✅ Complete LayerZero V2 OFT Adapter pattern implementation
• ✅ Bidirectional WHBAR bridge functionality (Hedera ↔ Sepolia)
• ✅ Automated contract deployment with environment-based configuration
• ✅ Comprehensive test coverage with autonomous infrastructure setup
• ✅ Production-ready documentation and troubleshooting guides
• ✅ Token economics validation ensuring 1:1 cross-chain parity
• ✅ Integration with Hedera and Ethereum block explorers
• ✅ LayerZero message tracking and validation

Fixes #3801

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

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[github-actions]

Test Results

 20 files   -  2  251 suites   - 44   32m 52s ⏱️ - 2m 55s
649 tests ± 0  644 ✅ + 1  5 💤 ±0  0 ❌  - 1 
665 runs   - 80  660 ✅  - 77  5 💤 ±0  0 ❌  - 3 

Results for commit a4a0a4c. ± Comparison against base commit c839172.

♻️ This comment has been updated with latest results.

[natanasow]

LGTM and fantastic job so far!

Most of the helper methods can be re-used in other examples, which was the initial goal 🚀.

Only commented for now because the PR is pretty big and I'll need some more time tomorrow to finish the review entirely.

[natanasow]

LGTM, some nits.