Note

Add in-memory executor mode to EmbeddedWorkflowExecutor

• Adds an inMemory flag to WorkflowExecutorEmbedOptions that builds the executor via buildInMemoryExecutor instead of a database-backed one, logging a warning about non-persistence.
• Adds mutual exclusivity validation: passing both inMemory and database throws an error.
• Removes fallback to DATABASE_URL and HTTP_PORT env vars; database is now required unless inMemory is true, and port defaults to 3400.
• Risk: any callers relying on DATABASE_URL or HTTP_PORT env var fallbacks will now get an explicit error instead of silent fallback behavior.

^{Macroscope summarized eadeb28.}