fix(cron): support per-job runtime overrides

Salvaged from PR #1292 onto current main. Preserve per-job model,
provider, and base_url overrides in cron execution, persist them in
job records, expose them through the cronjob tool create/update paths,
and add regression coverage. Deliberately does not persist per-job
api_key values.

tests/cron/test_scheduler.py

@@ -309,6 +309,57 @@ class TestRunJobConfigLogging:
             f"Expected 'failed to parse prefill messages' warning in logs, got: {[r.message for r in caplog.records]}"
 
 
+class TestRunJobPerJobOverrides:
+    def test_job_level_model_provider_and_base_url_overrides_are_used(self, tmp_path):
+        config_yaml = tmp_path / "config.yaml"
+        config_yaml.write_text(
+            "model:\n"
+            "  default: gpt-5.4\n"
+            "  provider: openai-codex\n"
+            "  base_url: https://chatgpt.com/backend-api/codex\n"
+        )
+
+        job = {
+            "id": "briefing-job",
+            "name": "briefing",
+            "prompt": "hello",
+            "model": "perplexity/sonar-pro",
+            "provider": "custom",
+            "base_url": "http://127.0.0.1:4000/v1",
+        }
+
+        fake_db = MagicMock()
+        fake_runtime = {
+            "provider": "openrouter",
+            "api_mode": "chat_completions",
+            "base_url": "http://127.0.0.1:4000/v1",
+            "api_key": "***",
+        }
+
+        with patch("cron.scheduler._hermes_home", tmp_path), \
+             patch("cron.scheduler._resolve_origin", return_value=None), \
+             patch("dotenv.load_dotenv"), \
+             patch("hermes_state.SessionDB", return_value=fake_db), \
+             patch("hermes_cli.runtime_provider.resolve_runtime_provider", return_value=fake_runtime) as runtime_mock, \
+             patch("run_agent.AIAgent") as mock_agent_cls:
+            mock_agent = MagicMock()
+            mock_agent.run_conversation.return_value = {"final_response": "ok"}
+            mock_agent_cls.return_value = mock_agent
+
+            success, output, final_response, error = run_job(job)
+
+        assert success is True
+        assert error is None
+        assert final_response == "ok"
+        assert "ok" in output
+        runtime_mock.assert_called_once_with(
+            requested="custom",
+            explicit_base_url="http://127.0.0.1:4000/v1",
+        )
+        assert mock_agent_cls.call_args.kwargs["model"] == "perplexity/sonar-pro"
+        fake_db.close.assert_called_once()
+
+
 class TestRunJobSkillBacked:
     def test_run_job_loads_skill_and_disables_recursive_cron_tools(self, tmp_path):
         job = {