feat(simulation): add deterministic fixed-step execution

[czlin7]

Summary

• add a small SimulationClock to decouple real frame time from fixed simulation ticks
• make pause, speed, maxTicks, and configured timestep operate through fixed-step simulation timing
• move simulation randomness to a seed-controlled SimulationWorld RNG
• pass RNG dependencies explicitly into AI/random helpers and use the same stream for spawning
• add foundation coverage for fixed-step timing and same-seed deterministic simulation
• split color and random helpers into focused utility headers

Why

The simulation previously advanced directly from variable frame delta and used separate hidden random sources. This made behavior dependent on frame timing and prevented reliable reproduction of a simulation run.

This change establishes a deterministic simulation foundation: with the same initial state, seed, fixed timestep, and tick sequence, the simulation follows the same path within the same execution environment.

Validation

• local Debug build completed successfully
• foundation tests passed: 1/1
• verified production simulation code contains no std::random_device or hidden thread_local RNG
• manually exercised pause/resume and simulation speed behavior during implementation