Upgrade a plugin to a new framework alpha with Codex CLI

Our rewrite with extra checks. The poster didn't test it.

Goal: Upgrade this plugin to the new Datasette alpha so all tests pass.

Inputs (fill in or confirm):
- The plugin repo path
- Upgrade guide path (~/dev/datasette/docs/upgrade-1.0a20.md)
- Test command (tadd)
- Python version and how tests are run in CI

Rules:
- Run the tests first and save the full error list.
- Read the upgrade guide and map each error to a guide section before editing.
- Make the smallest change that fixes each error; don't refactor unrelated code.
- Re-run tests after each group of fixes.
- Keep a short changelog entry describing the compatibility change.
- Read the whole upgrade guide first and list the changes that apply to this plugin.
- Fix one failing test at a time and rerun the suite after each change.
- Don't change test expectations just to make them pass; explain any test you think is wrong.
- Bump the Datasette dependency pin and note it in the changelog.

Checkpoint: Don't commit, bump versions or publish without asking.

If you get stuck: If an error isn't covered by the guide after two attempts, stop and show it to me. If a login, CAPTCHA or two-step code appears, stop and ask me to handle it; never guess or store passwords.

Verify before you finish: Final full test run must be green; list any warnings that remain.

Output: A summary of errors → fixes with file names, and the final test output.

Done when: the test suite passes on the new alpha with a minimal diff.