Create a public download link for an asset

Creates a temporary public download link for an asset. The link can optionally have an expiration. Requires the `canCreatePublicLink` permission (project/workspace admin roles) AND the `publicSharing` workspace capability — granted by every paid base plan and intentionally withheld from the Demo plan. Workspaces without the capability receive 403 `capabilityNotAvailable` with `errorData.capability = "publicSharing"`, which clients can use to prompt for an upgrade. Sets `hasActivePublicLink`, `everPublic`, and `publicAssetLinkIds` on the asset. Sends a notification and email to workspace admins if the creator is a project-level admin.

curl -X POST "https://example.com/assets/497f6eca-6276-4993-bfeb-53cbbbba6f08/public-links" \  -H "Content-Type: application/json" \  -d '{    "projectId": "5a8591dd-4039-49df-9202-96385ba3eff8"  }'

{  "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",  "token": "Ab3dEf9HiJ",  "assetId": "9179b887-04ef-4ce5-ab3a-b5bbd39ea3c8",  "projectId": "5a8591dd-4039-49df-9202-96385ba3eff8",  "creatorId": "688ebf54-d343-4104-8711-82c2feac534a",  "expires": "2019-08-24T14:15:22Z",  "status": "active",  "mode": "embed-download",  "publicUrl": "https://app.nurama.com/public-download/Ab3dEf9HiJ",  "isExpired": true,  "createdAt": "2019-08-24T14:15:22Z",  "updatedAt": "2019-08-24T14:15:22Z"}