Refactor project to transition from Rust backend to Node.js with Fastify; update Dockerfile and Docker configurations for new build process; enhance local development instructions in CONTRIBUTING.md; implement health checks in Docker Compose; update pnpm-lock.yaml with new dependencies for API and shared packages; revise README.md to reflect new stack and development setup.

packages/db/migrations/006_service_group_dns.sql

@@ -0,0 +1,7 @@
+CREATE TABLE service_group_dns_records (
+    group_id INTEGER NOT NULL REFERENCES service_groups(id) ON DELETE CASCADE,
+    dns_record_id INTEGER NOT NULL REFERENCES dns_records(id) ON DELETE CASCADE,
+    PRIMARY KEY (group_id, dns_record_id)
+);
+
+CREATE INDEX idx_service_group_dns_records_group_id ON service_group_dns_records(group_id);