Human Intervention node displays unresolved variable references after page refresh during execution

### Self Checks

- [x] I have read the [Contributing Guide](https://github.com/langgenius/dify/blob/main/CONTRIBUTING.md) and [Language Policy](https://github.com/langgenius/dify/issues/1542).
- [x] This is only for bug report, if you would like to ask a question, please head to [Discussions](https://github.com/langgenius/dify/discussions/categories/general).
- [x] I have searched for existing issues [search for existing issues](https://github.com/langgenius/dify/issues), including closed ones.
- [x] I confirm that I am using English to submit this report, otherwise it will be closed.
- [x] 【中文用户 & Non English User】请使用英语提交，否则会被关闭 ：）
- [x] Please do not modify this template :) and fill in all the required fields.

### Dify version

1.15.0

### Cloud or Self Hosted

Self Hosted (Docker)

### Steps to reproduce

1. Create a chatflow/app that uses a Human Intervention node.
2. Configure the Human Intervention node's form content to reference an upstream text variable.
3. Run the app and reach the pending human intervention card.
4. Refresh the app page while the workflow is still waiting for human action.
5. Check the form content shown in the human intervention card.
6. Select one of the available actions.

Possibly related to #37588, but this report is specifically about the page refresh case: after refresh, the card initially renders the raw variable reference and only resolves it after an action is selected.

### ✔️ Expected Behavior

After refreshing the page during execution, the form content only shows the raw variable reference, for example {{#1778488854176.text#}}.

The actual text value is not visible until one of the actions is selected.

From the attached screenshots:
- Before selecting an action, the form content displays the variable reference.
- After selecting an action, the concrete text value is displayed.

### ❌ Actual Behavior

After refreshing the page during execution, the form content only shows the raw variable reference, for example {{#1778488854176.text#}}.

The actual text value is not visible until one of the actions is selected.

From the attached screenshots:
- Before selecting an action, the form content displays the variable reference.
- After selecting an action, the concrete text value is displayed.