Scheduled view refreshes should use application-layer scheduling instead of pg_cron

[kbighorse]

Problem

pg_cron is required by db/initialization.py, core/initializers.py, and the pygeoapi migration (d5e6f7a8b9c0). It hard-fails when unavailable, blocking local development and test runs on standard PostgreSQL installs that don't ship pg_cron.

Proposal

• Move scheduled tasks (materialized view refreshes) to the application layer (e.g. APScheduler, Celery beat, or a simple cron job)
• Remove pg_cron as a database dependency
• Make db/initialization.py and core/initializers.py gracefully skip pg_cron in the interim

Current workaround

Skip the hard-fail checks locally by patching initialization.py and initializers.py to treat pg_cron as optional.

[github-actions]

Linked Jira ticket created: BDMS-627