feat(wfe-core): add test support with in-memory providers and test suites

InMemoryPersistenceProvider, InMemoryLockProvider, InMemoryQueueProvider,
InMemoryLifecyclePublisher behind test-support feature flag.

Shared test suite macros: persistence_suite!, lock_suite!, queue_suite!
that run the same tests against any provider implementation.

wfe-core/src/test_support/fixtures.rs

@@ -0,0 +1,62 @@
+use chrono::Utc;
+
+use crate::models::{Event, EventSubscription, ExecutionError, WorkflowInstance};
+
+/// Create a sample `WorkflowInstance` for testing.
+pub fn sample_workflow_instance() -> WorkflowInstance {
+    WorkflowInstance::new("test-workflow", 1, serde_json::json!({"key": "value"}))
+}
+
+/// Create a sample `Event` for testing.
+pub fn sample_event() -> Event {
+    Event::new(
+        "order.created",
+        "order-123",
+        serde_json::json!({"amount": 42}),
+    )
+}
+
+/// Create a sample `EventSubscription` for testing.
+pub fn sample_subscription() -> EventSubscription {
+    EventSubscription::new("wf-1", 0, "ptr-1", "order.created", "order-123", Utc::now())
+}
+
+/// Create a sample `ExecutionError` for testing.
+pub fn sample_execution_error() -> ExecutionError {
+    ExecutionError::new("wf-1", "ptr-1", "something went wrong")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn sample_workflow_instance_has_expected_fields() {
+        let instance = sample_workflow_instance();
+        assert_eq!(instance.workflow_definition_id, "test-workflow");
+        assert_eq!(instance.version, 1);
+    }
+
+    #[test]
+    fn sample_event_has_expected_fields() {
+        let event = sample_event();
+        assert_eq!(event.event_name, "order.created");
+        assert_eq!(event.event_key, "order-123");
+    }
+
+    #[test]
+    fn sample_subscription_has_expected_fields() {
+        let sub = sample_subscription();
+        assert_eq!(sub.workflow_id, "wf-1");
+        assert_eq!(sub.event_name, "order.created");
+        assert_eq!(sub.event_key, "order-123");
+    }
+
+    #[test]
+    fn sample_execution_error_has_expected_fields() {
+        let err = sample_execution_error();
+        assert_eq!(err.workflow_id, "wf-1");
+        assert_eq!(err.execution_pointer_id, "ptr-1");
+        assert_eq!(err.message, "something went wrong");
+    }
+}