Vendor pyprima optimization code and drop scipy

[jonchang]

Note

Vendors pyprima COBYLA and a bounded scalar minimizer to remove SciPy, rewrites optimization in tact/lib.py, updates tests and tooling, and bumps dev dependencies.

• Core/Optimization:
  • Replace SciPy optimizers with vendored pyprima COBYLA (pyprima_minimize) and vendored minimize_scalar_bounded in tact/lib.py.
  • Add robust parameter/exception handling in likelihood wrappers; rework two_step_optim to COBYLA; adjust Yule optimizer and errors.
• Vendoring:
  • Add tact/vendor/pyprima (COBYLA) with compatibility shims and patches; add tact/vendor/scipy_optimize/minimize_scalar_bounded.
  • Add tact/vendor/README.md and patching infrastructure; include update_vendor.sh script.
• Tests:
  • Update CLI invocations to list-style script_runner.run([...]).
  • Relax test_bd_optim tolerances.
• Config/Deps:
  • Remove SciPy from runtime; keep numpy; bump dev deps (pytest, hypothesis, pytest-*).

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