Deterministic Physics for Replay and Undo Systems

Act as a Network and Systems Architect. Architect a rigidly deterministic physics simulation within React Three Fiber specifically engineered to support flawless 'Kill Cam' game replays or complex undo mechanics. You must brutally force the underlying physics engine to execute on a strictly [FIXED_TIMESTEP] (e.g., 1/60s), completely divorcing it from the inherently variable browser `requestAnimationFrame` loop. Detail the exact memory-management architecture required to serialize and save deep JSON snapshots of all RigidBody transform matrices and velocities at a specific [STATE_SNAPSHOT_INTERVAL]. Mandate the injection of a strict [PRNG_SEED] (Pseudo-Random Number Generator) to guarantee that any procedural forces or chaotic collisions resolve with mathematically identical results across different browsers and sessions.