Frontend should implement node self-validation when loading custom nodes, with one-click fix support

As a custom node developer, one pain point is that when ComfyUI loads a workflow and its nodes, it uses the node definitions stored in the workflow. However, if I update my node—for example, adding or deleting widgets, changing widget order, or modifying types—the workflow doesn't reflect these changes. When running the workflow, errors occur (typically "value not in option list") because I've modified the backend Python code.

I would like the frontend to detect and highlight problematic nodes with a yellow warning when loading the workflow. Then, when selecting such a node, a prominent "Fix it" button should appear, allowing the node to be rebuilt using the latest backend definition.

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-7941-Frontend-should-implement-node-self-validation-when-loading-custom-nodes-with-one-cli-2e46d73d365081f09819d393b0e91053) by [Unito](https://www.unito.io)