docs: card1 (версии, документ, auth Postgres_TG_Bots); миграция 002 parent_id+unique active; спринт1+бэклог под Node

Made-with: Cursor

backend/src/db/migrations/002_test_version_parent_and_active_unique.sql

@@ -0,0 +1,14 @@
+-- Version chain: parent link + at most one active version per test chain
+-- Aligns with docs/revision_task/card1.md (V.1)
+
+ALTER TABLE test_versions
+  ADD COLUMN IF NOT EXISTS parent_id UUID REFERENCES test_versions(id) ON DELETE RESTRICT;
+
+COMMENT ON COLUMN test_versions.parent_id IS 'Previous version in chain; NULL for first version';
+
+-- Only one active version per tests.id (chain)
+CREATE UNIQUE INDEX IF NOT EXISTS uq_test_versions_one_active_per_test
+  ON test_versions (test_id)
+  WHERE is_active = true;
+
+CREATE INDEX IF NOT EXISTS idx_test_versions_parent_id ON test_versions (parent_id);