fix(arch-030,arch-047): workflow steps resolve plugins via contracts at runtime

app/plugins/builtins/automation/contracts.py

@@ -63,6 +63,11 @@ class AutomationContract:
     # ─── agent_comm ───
     send_agent_message = staticmethod(send_agent_message)
 
+    @classmethod
+    def get_function(cls, name: str):
+        """Return a callable exposed by this contract, or None if absent."""
+        return getattr(cls, name, None)
+
 
 # ─── self-registration ───