chore(deps): bump pyo3 + numpy to 0.29 in /rust (RUSTSEC-2026-0176/0177)

Bumps the Rust backend's pyo3 and numpy crates 0.28 -> 0.29 in lockstep
(numpy 0.29 requires pyo3 ^0.29), resolving two RustSec advisories that
affect pyo3 < 0.29:

- RUSTSEC-2026-0176 (GHSA-36hh-v3qg-5jq4, High): out-of-bounds read in the
  PyList/PyTuple nth/nth_back iterators.
- RUSTSEC-2026-0177 (GHSA-chgr-c6px-7xpp, Medium): missing Sync bound on
  PyCFunction::new_closure closures.

Neither vulnerable path is reachable in this crate: the Rust source has no
PyList/PyTuple iteration, no PyCFunction::new_closure, and builds no
free-threaded wheels. This is a binding-layer-only change -- the math/RNG
crates (ndarray 0.17, faer 0.24, rand 0.10, rand_xoshiro 0.8) are unchanged,
and the Rust-backend bit-identity snapshot test confirms zero numerical drift.

Supersedes Dependabot PRs #537 (pyo3) and #538 (numpy), which each bumped one
crate alone and so could not resolve (the numpy/pyo3 version constraint
couples them).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: igerber

CHANGELOG.md

@@ -31,6 +31,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `treatment_fraction` remains inert (balanced 2×2×2); pass `group_frac`/`partition_frac`
   via `data_generator_kwargs`. See `docs/methodology/REGISTRY.md` §PowerAnalysis.
 
+### Security
+- **Bumped the Rust backend's `pyo3` and `numpy` crates 0.28 → 0.29.** Resolves two RustSec
+  advisories in `pyo3 < 0.29` — RUSTSEC-2026-0176 (out-of-bounds read in `PyList`/`PyTuple`
+  `nth`/`nth_back`, High) and RUSTSEC-2026-0177 (missing `Sync` bound on
+  `PyCFunction::new_closure`, Medium). Neither vulnerable path was reachable in this crate
+  (no `PyList`/`PyTuple` iteration, no `new_closure`, no free-threaded wheels); `numpy` 0.29 is
+  bumped in lockstep because it requires `pyo3` ^0.29. No API or numerical change — both crates
+  are FFI/binding layers, and the math/RNG crates (`ndarray`, `faer`, `rand`, `rand_xoshiro`)
+  are unchanged.
+
 ## [3.5.2] - 2026-06-08
 
 ### Added

rust/Cargo.toml

@@ -21,9 +21,9 @@ accelerate = ["ndarray/blas", "dep:blas-src", "blas-src/accelerate"]
 openblas = ["ndarray/blas"]
 
 [dependencies]
-# PyO3 0.28 supports Python 3.9-3.14
-pyo3 = "0.28"
-numpy = "0.28"
+# PyO3 0.29 supports Python 3.9-3.14
+pyo3 = "0.29"
+numpy = "0.29"
 ndarray = { version = "0.17", features = ["rayon"] }
 rand = "0.10"
 rand_xoshiro = "0.8"