Make a node to uload models and clear the nodes cahe.

### Feature Idea

As in the title. Make a node that will unload the models and clear the node cache, i.e., make a node to automate pushing those two little buttons in the ui. Is that hard to do. If some say "there are many ways to do that." Fine they do have to use it. There is no cleaner way to do it. Just make the node. Using Minimax 3, if you don't have something monitoring your vram usage, you won't notice that about half the time it doesn't unload the model after the run. If you change anything and rerun it, it will take half a day for the model to initialize. You might as well shut down ComfyUI and restart it. You have to remember each time to hit those two buttons to unload the models and node cache. That's just dumb. Is a node to automate it that difficult to make?

### Existing Solutions

_No response_

### Other

_No response_

No implementation files or tests are named; start by tracing the two UI buttons for model unloading and node-cache clearing. Confirm how those actions are exposed to the graph, and define done as a node that triggers both reliably for the reported rerun and VRAM-usage scenario.

Written by the indexing model from the issue text.