src/activity_core/seed.py: inserts one example ActivityDefinition
('example-heartbeat', cron every minute, static context source,
log_message task template). Idempotent — skips by name on re-run.
Run with:
ACTCORE_DB_URL=postgresql+asyncpg://actcore:actcore@localhost:5433/actcore \
python -m activity_core.seed
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
