Installs a pytest11 entry point so that every Datasette() constructed
inside a pytest_runtest_call phase is auto-closed at the end of the test.
Fixture-scoped instances are untouched. Opt out via the
datasette_autoclose = false ini option.
This gives large test suites a safety net against FD exhaustion and leaked
write threads from the now-default temp-disk internal database without
requiring every existing test to be rewritten.
Refs #2692
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>