chore: lift the numpy<2.5 dev-lock constraint once stubtest handles PEP 695 aliases

[t-uda]

Context

PR #132 (Poetry→uv migration) added a temporary constraint to pyproject.toml:

[tool.uv]
constraint-dependencies = ["numpy<2.5"]

numpy 2.5 re-exports numpy.typing.NDArray as a PEP 695 type alias, which current mypy/stubtest misreports when validating this package's .pyi stubs on Python ≥ 3.12, breaking the stubtest CI step. The constraint only pins the development lockfile (uv.lock); published package metadata still declares numpy>=1.26, so end users are unaffected.

Task

• Periodically retry with new mypy releases (uv lock --upgrade-package mypy, then uv run --group dev stubtest ...); the upstream fix lands in mypy/typeshed, not in this repo.
• When stubtest passes against numpy ≥ 2.5, remove constraint-dependencies from [tool.uv], run uv lock, and confirm the full AGENTS.md checklist.
• If instead our stubs are at fault (check whether NDArray usage in src/ellphi/*.pyi can be expressed compatibly), fix the stubs and remove the constraint.

Small, self-contained chore — suitable for an implementing agent. Base the PR on the current release branch per CONTRIBUTING.md.