Add notify_task_change() and notify_story_change() PL/pgSQL functions
plus AFTER INSERT/UPDATE/DELETE triggers on tasks and stories. Each
write emits a JSONB payload on the 'scrum4me_changes' channel with
op, entity, id, product_id, sprint_id, assignee_id and (for UPDATE)
the list of changed columns. Tasks resolve product/sprint/assignee
via their parent story so the SSE handler can filter without an extra
DB roundtrip.
The migration is a side-effect-only change (no Prisma model/schema
diff) so the Prisma Client and TypeScript types are unaffected.
Verified locally with a node-pg LISTEN client: both task and story
mutations produce the expected payload within milliseconds.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>