Promote the Unreleased changelog block to 10.0.0 and bump the package
version in pyproject.toml, uv.lock, and CITATION.cff.

Major, not minor. The release carries one breaking change — #84 removed
the `method: list` annotation encoding in favor of `split_by`, so a table
config still declaring it no longer validates. Shipping that as 9.2.0
would have let a `~=9.1` compatible-release pin cross it silently, the
exact failure 9.0.0 was cut to correct. The changelog entry leads with
the breaking change and states the reason for the major bump.

The release covers everything on main since 9.1.0:
- `method: list` removed in favor of `split_by`, with the stale-config
  migration pointer `encoding-list-method-removed` (#84).
- `nullable` qualifiers — a `method: column` qualifier may declare
  `nullable: true` to keep the edge and omit the qualifier on a blank or
  unresolvable cell, instead of dropping the edge (#85).

No documentation drift this time: both feature PRs updated
docs/configuration/table.md in place, and llms.txt maps no new module.
Only the two version examples needed bumping — the `--version` sample in
docs/cli.md and the _prebuilt_fullmap_urls docstring, both still 9.1.0.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NZWbF4BEP9Gd9BD7UTx3HF