feat(scheduler): add scheduled jobs with channel-aware delivery

Introduce persisted cron/interval jobs, gateway scheduler loop, worker turns,
and admin CRUD/edit UI. Route proactive reminders via the originating chat
channel (WhatsApp vs WeChat), harden Weixin outbound with durable queue and
PG-compatible polling, and fix chat UI to show each scheduled reminder separately.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_gateway_cron_service.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+import os
+import tempfile
+import unittest
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+from interfaces.gateway.http_adapter import dispatch_gateway_http_method
+from svc.persistence.assistant_store import reset_assistant_store_singleton
+from svc.persistence.sqlite_store import SqliteStore
+
+
+class GatewayCronServiceTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self._tmp = tempfile.TemporaryDirectory(ignore_cleanup_errors=True)
+        self.db = Path(self._tmp.name) / "cron.sqlite"
+        os.environ["OPS_ASSISTANT_DB_PATH"] = str(self.db)
+        os.environ["AIA_ASSISTANT_DB_BACKEND"] = "sqlite"
+        reset_assistant_store_singleton()
+        self.store = SqliteStore(str(self.db))
+        t = self.store.create_tenant("default")
+        self.tenant_id = str(t["id"])
+
+    def tearDown(self) -> None:
+        reset_assistant_store_singleton()
+        self._tmp.cleanup()
+
+    def test_cron_add_and_list(self) -> None:
+        once_at = (datetime.now(timezone.utc) + timedelta(hours=2)).isoformat()
+        add = dispatch_gateway_http_method(
+            "cron.add",
+            {
+                "name": "gw job",
+                "schedule": once_at,
+                "schedule_kind": "once",
+                "tenant_id": self.tenant_id,
+                "prompt": "hello",
+            },
+        )
+        self.assertTrue(add.get("ok"), add)
+        lst = dispatch_gateway_http_method("cron.list", {"tenant_id": self.tenant_id})
+        self.assertTrue(lst.get("ok"), lst)
+        payload = lst.get("payload") or {}
+        self.assertGreaterEqual(len(payload.get("items") or []), 1)
+
+
+if __name__ == "__main__":
+    unittest.main()