test: move domain tests to tests/

Self dev-dep w/ test-helpers for domain::testing. Also moved social blanket-impl + InMemoryStore tests (public API only). No private-item exceptions.

crates/domain/tests/errors/errors_test.rs

@@ -0,0 +1,31 @@
+use domain::errors::DomainError;
+
+#[test]
+fn infrastructure_error_is_transient() {
+    assert!(DomainError::InfrastructureError("network timeout".into()).is_transient());
+}
+
+#[test]
+fn not_found_is_not_transient() {
+    assert!(!DomainError::NotFound("thing".into()).is_transient());
+}
+
+#[test]
+fn validation_error_is_not_transient() {
+    assert!(!DomainError::ValidationError("bad input".into()).is_transient());
+}
+
+#[test]
+fn unauthorized_is_not_transient() {
+    assert!(!DomainError::Unauthorized("token expired".into()).is_transient());
+}
+
+#[test]
+fn forbidden_is_not_transient() {
+    assert!(!DomainError::Forbidden("no access".into()).is_transient());
+}
+
+#[test]
+fn invalid_rating_is_not_transient() {
+    assert!(!DomainError::InvalidRating { max: 5, given: 9 }.is_transient());
+}