Tracking: Custom Nodelauncher

[jenpaff]

Feature Description

Restructure the Consensus Engine to be flexbile and reusable

Problem Statement

Not all nodes use the Engine API as the consensus engine; our current tree implementation lacks the flexibility required for reuse across different contexts.

Acceptance Criteria

• The Engine module is restructured with clear separation of concerns
• We can successfully implement a custom consensus engine via NodeLauncher
• Existing functionality continues to work without breaking changes
• Documentation and examples are provided for creating custom Engine implementations
• Tests to verify that the restructured components work correctly