Copy-paste reference of Subgraph or nodes

### Feature Idea

### Currently,
when using multiple identical subgraphs in a workflow, modifying a property - such as a path to a model - requires editing each.
Example: template of WAN 6 frames to video. What user now should do to change path for model or strength: edit each of 5 sub-graphs or make external parameter.

### Proposed to
Implement a feature that allows users to create linked clone of node or subgraphs, which reference a single instance. When an editable property on the source instance is modified, all linked clones automatically update to reflect that change.

### Existing Solutions

_No response_

### Other

_No response_

No file, test, or entry point is named in the issue. Start by locating the workflow node and subgraph handling, then define how linked clones are created and which editable source properties must propagate to all references.

Written by the indexing model from the issue text.