Function collectEmbeddedFileIds

collectEmbeddedFileIds(content: JSONContent | null | undefined): string[]
Walk a TipTap JSON document and collect every assignmentEmbed node's fileId. Returns a deduplicated, insertion-ordered list.

Use this to discover which files an assignment references inline so they can be shared with assignees, fetched, or pre-loaded alongside the assignment file itself.
Parameters
- content: JSONContent | null | undefined
  The AssignmentFile's content JSON (or any TipTap node). Safely handles null/undefined and non-tree shapes.
Returns string[]
Array of unique fileIds in document order. Empty when there are no embeds, no fileIds, or the input isn't a node tree.
Example
```
const fileIds = collectEmbeddedFileIds(assignment.content);
// ['file-abc123', 'file-def456']
```
- Defined in packages/react-assignments/src/utils/embedUtils.ts:32