feat(cron): bind scheduled automations to sessions

tests/agent/test_session_manager_history.py

@@ -1,4 +1,5 @@
 from nanobot.session.manager import Session, SessionManager
+from nanobot.session.routing import SESSION_ROUTING_METADATA_KEY
 
 
 def _assert_no_orphans(history: list[dict]) -> None:
@@ -432,6 +433,11 @@ def test_fork_session_before_user_index_copies_only_prefix(tmp_path):
     source.metadata["webui"] = True
     source.metadata["title"] = "Old title"
     source.metadata["goal_state"] = {"status": "active", "objective": "do not inherit"}
+    source.metadata[SESSION_ROUTING_METADATA_KEY] = {
+        "channel": "websocket",
+        "chat_id": "source",
+        "metadata": {},
+    }
     source.add_message("user", "round1")
     source.add_message("assistant", "answer1")
     source.add_message("user", "round2 fork me")
@@ -450,6 +456,7 @@ def test_fork_session_before_user_index_copies_only_prefix(tmp_path):
     assert forked.metadata["webui"] is True
     assert "title" not in forked.metadata
     assert "goal_state" not in forked.metadata
+    assert SESSION_ROUTING_METADATA_KEY not in forked.metadata
     saved = manager.read_session_file("websocket:fork")
     assert [m["content"] for m in saved["messages"]] == ["round1", "answer1"]