refactor: tighten backend, flows, frontend, tests; push flows to Langflow

backend/app/settings.py

@@ -1,5 +1,6 @@
 from pathlib import Path
 
+from pydantic import computed_field
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 # Repo-root .env (shared with the compose stack). Real environment variables
@@ -53,6 +54,7 @@ class Settings(BaseSettings):
     smtp_username: str = ""
     smtp_password: str = ""
 
+    @computed_field  # type: ignore[misc]
     @property
     def admin_email_list(self) -> list[str]:
         return [e.strip().lower() for e in self.admin_emails.split(",") if e.strip()]