Release django-ox 1.8.0

[PhiLily]

• What and why: Release 1.8.0 with schedule safety fixes, the stable create_schedules API, beat importer corrections, MySQL shared-Worker lease renewal and PostgreSQL pool recovery changes. Upgrade workers so invalid stored schedules cannot stop other schedules or queued tasks. Document cleanup of existing rows and checks for earlier importer output. The unreadable PostgreSQL year-10000 row must be deleted; admin access and API pausing do not work for it. The drain-based pool fix requires psycopg_pool 3.3.0 or later. Version 3.2.x retains the legacy sweep and is excluded from that fix. Recommend 3.3.3 or newer. No shutdown deadline is added. Set the version, date the CHANGELOG 2026-10-04, and update SECURITY.md, docs/pro.md and docs/stability.md. No database migration is required.
• Tests: The interval overflow was reproduced on SQLite. The PostgreSQL stored-bound failure was reproduced on every release from 1.2.0 through 1.7.0 using Django 6.0.8 and Python 3.12, not each release's own support matrix. Pooled PostgreSQL tests covered lost connections, terminated sessions, checkout exhaustion and recovery with health checks. Real manage.py ox_worker stop tests covered psycopg_pool 3.3.3 and 3.2.8. The CHANGELOG records the observed timings, connection opens and limits of those tests.
• Changelog: entry dated with upgrade guidance. Security, Fixed, Changed and Added cover schedule validation and isolation, batch creation, importer behavior, MySQL renewal and pool recovery. Keep the security register and its backend distinctions intact.