* refactor: use TBB for concurrent hash maps and parallelize chunk processing
* fix: tbb link fail
* refactor(chunk): remove biome check for caves in rivers and oceans
* refactor(random): replace std distributions with custom implementations
Avoid overhead and platform-dependent behavior of `<random>` distributions by using direct engine operations and integer arithmetic. This ensures deterministic, cross-platform results and improves performance.
* refactor(generation): use chunk seed for cave and river paths
- Use per-chunk seed instead of global path_id for cave and river generation.
- Remove unused m_sum variables and m_path_id members.
- Clamp river yaw within 10 degrees of initial direction.
- Fix river radius interpolation (use t instead of 1-t).
- Lower sea level from 64 to 63.
