Add CI/CD test pipeline and unit tests for account, order, payment, and product

[rasadov]

Summary

• Add GitHub Actions workflow (CI/CD Test Pipeline) that runs unit tests on every push/PR.
• Add service and repository unit tests for order, payment, and product, following the same patterns as account.
• Add orchestrator for E2E tests for managing execution order of tests
• Move GraphQL E2E tests into tests/e2e/ and exclude them from the default unit test run.
• Switch in-memory SQLite test setup to the pure Go driver (github.com/glebarez/sqlite) so repository tests run without CGO/gcc on Windows.
• Fix flaky account service tests by validating JWT claims instead of comparing raw token strings (CI runs with -race, which slows bcrypt and can cause tokens to differ by iat).

Unit tests run with -race and exclude tests/e2e. E2E job starts the full Docker Compose stack and runs ./tests/e2e/....

Other changes

• docker-compose.yaml: optional DODO_API_KEY / DODO_TEST_MODE env vars for the payment service (used in CI via secrets).
• order/internal/repository.go: use Model(&models.Order{}) in UpdateOrderPaymentStatus for SQLite-compatible updates in tests.

Test plan

• Unit tests pass locally: go test ./account/tests/... ./order/tests/... ./payment/tests/... ./product/tests/...
• CI unit job passes on this PR
• GraphQL E2E suite still passes against a running stack: go test ./tests/e2e/...