Cut 16.6.2 and bump the package version in pyproject.toml, uv.lock, and
CITATION.cff.

Patch: two fix PRs ship. `number_of_cases` is now emitted as a JSON
integer instead of raw source text — the slot is typed `int` on
biolink-model but sat outside `lib.numeric_columns`, so string cells
shipped on the edge NDJSON and left the graph type-inconsistent edge to
edge (#139). `--release` builds no longer reuse section parquets cached
by other build modes: `--head`, `--release`, and `--qc` now cache under
distinct suffixes via `_section_store_path`, closing a cache-poisoning
bug where release filters were silently skipped and `applied_to_treat`
edges with `number_of_cases < 25` shipped (#140). The release-mode
`drop_low_number_of_cases` and `drop_zero_effect_size` filters also
tolerate non-numeric cells (e.g. a TSV header row read as data) instead
of crashing with `InvalidOperationError` (#140).

Changelog:
- Versioned the Unreleased section as 16.6.2 and gave the
  `number_of_cases` entry its missing PR link (#139).

Docs: none needed here — #140's `cli.py` change is an internal cache-key
helper and #139 changes emission types only; both are fully documented
in their changelog entries.

Testing:
- uv run pytest -q -> 1253 passed, 3 skipped (96% coverage)
- uv run ruff check . && uv run ruff format --check . && uv run pyright -> clean / 0 errors
- uv lock --check -> up to date
- uv run mkdocs build --strict -> clean