feat(schema): add notify_pbi_change trigger so PBI INSERT/UPDATE/DELETE emits NOTIFY on scrum4me_changes (#58)

Co-authored-by: Scrum4Me Agent <30029041+madhura68@users.noreply.github.com>

prisma/migrations/20260502190200_add_pbi_notify_trigger/migration.sql

@@ -0,0 +1,53 @@
+-- Add notify_pbi_change() function and pbis_notify_change trigger so that
+-- INSERT/UPDATE/DELETE on pbis emits a pg_notify on 'scrum4me_changes'.
+-- Payload field names match BacklogPbi directly (no client-side rename needed).
+
+CREATE OR REPLACE FUNCTION notify_pbi_change() RETURNS trigger AS $$
+DECLARE
+  rec record;
+  payload jsonb;
+BEGIN
+  IF TG_OP = 'DELETE' THEN
+    rec := OLD;
+  ELSE
+    rec := NEW;
+  END IF;
+
+  payload := jsonb_build_object(
+    'op', CASE TG_OP
+            WHEN 'INSERT' THEN 'I'
+            WHEN 'UPDATE' THEN 'U'
+            WHEN 'DELETE' THEN 'D'
+          END,
+    'entity', 'pbi',
+    'id', rec.id,
+    'product_id', rec.product_id,
+    'title', rec.title,
+    'code', rec.code,
+    'priority', rec.priority,
+    'status', rec.status,
+    'sort_order', rec.sort_order,
+    'created_at', rec.created_at
+  );
+
+  IF TG_OP = 'UPDATE' THEN
+    payload := payload || jsonb_build_object(
+      'changed_fields',
+      COALESCE((
+        SELECT jsonb_agg(n.key)
+        FROM jsonb_each(to_jsonb(NEW)) n
+        JOIN jsonb_each(to_jsonb(OLD)) o USING (key)
+        WHERE n.value IS DISTINCT FROM o.value
+      ), '[]'::jsonb)
+    );
+  END IF;
+
+  PERFORM pg_notify('scrum4me_changes', payload::text);
+  RETURN rec;
+END;
+$$ LANGUAGE plpgsql;
+
+DROP TRIGGER IF EXISTS pbis_notify_change ON pbis;
+CREATE TRIGGER pbis_notify_change
+  AFTER INSERT OR UPDATE OR DELETE ON pbis
+  FOR EACH ROW EXECUTE FUNCTION notify_pbi_change();