BUG: seed parachute pressure noise with per-instance RNG (#1091)

[thatrandomasiandev]

Summary

• Give Parachute an optional seed and a per-instance numpy.random.Generator so pressure noise no longer draws from the process-global RNG (Fixes #1091).
• Thread a derived noise seed from StochasticParachute into created parachutes when Monte Carlo seeds the model.
• Add unit tests for same-seed reproducibility, different-seed divergence, default unseeded behavior, and independence from the global NumPy RNG.

Test plan

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 PYTHONPATH=. pytest tests/unit/rocket/test_parachute_noise_seed.py tests/unit/rocket/test_parachute.py tests/unit/stochastic/test_stochastic_parachute.py
• Spot-check that two Monte Carlo runs with the same root seed produce identical parachute noise sequences when noise is non-zero