refactor: account model overhaul

dev/docs/integration-tests.md

@@ -0,0 +1,21 @@
+# Integration tests (Go + testcontainers)
+
+## Requirements
+
+- A working Docker daemon reachable from the devcontainer.
+  - Recommended: `.devcontainer/devcontainer.json` includes `docker-outside-of-docker`, which uses the host/Codespaces Docker.
+  - Alternative: switch to `docker-in-docker` if you don’t have host Docker access.
+
+## Run
+
+From `apps/backend`:
+
+```bash
+go test -tags=integration ./internal/drexa -run TestRegistrationFlow -count=1
+```
+
+Notes:
+
+- The first run pulls `postgres:16-alpine` (needs network access).
+- Tests are tagged `integration` so they never run in normal `go test ./...` by accident.
+- If Docker isn’t available, the test skips (rather than failing).