Expand the Python binding to cover the full C API and publish wheels #117

Part of #108 (health-review epic).

Context

The ctypes Python binding currently exposes only get_version, get_stp, get_stp_table, get_default_table, and get_csda_table. The C library offers considerably more, and a first-class Python wrapper is a stated goal alongside the WASM web app.

Gaps

Not yet wrapped:

• Inverse stopping power (dedx_get_inverse_stp) and inverse CSDA (dedx_get_inverse_csda).
• Unit conversion (convert_units / future dedx_convert_units, see refactor: namespace public convert_units() as dedx_convert_units() #112).
• Custom compounds (element ids + mass fractions / atom counts).
• Per-element I-value override (see simple override of elemental I-values #6).
• Name/list/query helpers (dedx_get_*_name, dedx_get_*_list, min/max energy), and the planned valid-combination query API (Add query API for valid (program, ion, material) combinations to support GUI/frontend development #79).
• Surfacing the Bragg-fallback flag (Make Bragg/stoichiometric fallback transparent (surface bragg_used) and add accuracy tests #111).

Distribution gap

The package is dev-install only (requires a locally built .so via LIBDEDX_SO). There are no published wheels.

Proposed change

• Extend python/libdedx/_api.py (and the .pyi stubs) to wrap the full API, with numpy-friendly array helpers and Pythonic error handling (raise on *err).
• Build and publish wheels (manylinux/macOS/Windows) bundling the native library, to PyPI, via CI.

Acceptance criteria

• Inverse stp, inverse csda, unit conversion, custom compounds, I-value override, and name/list queries are exposed and tested.
• Bragg-fallback provenance is queryable from Python (depends on Make Bragg/stoichiometric fallback transparent (surface bragg_used) and add accuracy tests #111).
• pip install libdedx works from a published wheel without a manual native build (CI publishes wheels).
• Type stubs (__init__.pyi) and ruff/pytest pass for the expanded surface.

References

Depends on / relates to: #112, #111, #79, #6