AIM-004: Implement hexagonal architecture for Bitcoin Layer 2 solutions

Integrate core Layer 2 protocol adapters with Bitcoin ecosystem:
- BOB (Bitcoin Optimistic Blockchain) adapter with PSBT support
- RGB Protocol integration with Taproot asset capabilities (BIP-341)
- RSK Sidechain with Bitcoin-backed verification
- Modular framework for future Layer 2 solutions

Technical Implementation:
- Hexagonal architecture pattern for protocol isolation
- Port/adapter separation for clean interfaces
- Comprehensive test suite with 100% coverage for consensus code
- Security validation against BIP standards
- Prometheus metric endpoints for performance monitoring

Compliance:
- [x] BIP 341/342 (Taproot)
- [x] BIP 174 (PSBT)
- [x] Miniscript Support
- [ ] Testnet Validation (pending)

References official Bitcoin Improvement Proposals (BIPs)
Related to: AIR-342, AIT-367

Signed-off-by: bo_thebig <botshelomokoka@gmail.com> 