fix(indexing): audit factual contracts and close validation gaps

[d-v-b]

🤖 AI text below 🤖

Correct factual claims in zarr-indexing's documentation, source comments, examples, and testing contracts, and fix the correctness defects exposed while checking those claims.

Runtime changes:

• Reject mixed boolean/integer wire arrays and coordinates outside intp before NumPy can coerce or wrap them.
• Reject computed canonical bounds outside signed 64-bit range and enforce the existing input-rank limit consistently across message forms, preserving normalization idempotence.
• Route intersections with shared affine/index-array dependencies to the explicit unsupported path instead of returning extra coordinates. Planning this mixed case now raises NotImplementedError, consistent with its general classification.
• Group signed chunk-coordinate tuples without collisions; distinct chunks such as (-1, 0) and (0, -1) must remain separate.

Expand regression coverage across integer widths, indexing modes, origins, normalization boundaries, map order, negative chunk IDs, repeated points, and one-/two-axis dependencies. Keep main's existing unsigned-selector fix.

The documentation now distinguishes structural box classification from density/order, actual NumPy compatibility from tested examples, metadata inspection from tokenization reads, and parent partition context from direct part resolution. It also corrects TensorStore wire/partition comparisons, cache and benchmark claims, and source integration descriptions. Finite index_array_bounds remain unenforced during engine loading and are explicitly documented as a limitation.

Validation against fork main ba883a556:

• Full package tests and doctests: 1,521 passed, no skips, including TensorStore 0.1.84 and Dask 2026.8.0.
• Strict documentation build passed.
• Applicable changed-file repository checks passed, including Ruff, mypy, codespell, and numpydoc.
• Package Pyright check: 0 errors, 90 warnings with the Hatch interpreter explicitly selected.

[d-v-b]

🤖 AI text below 🤖

The agent closed this draft as superseded: its head is byte-identical under packages/zarr-indexing to the squash commit that merged upstream as zarr-developers#4345.