Unarchive a feature flag

{  "id": "ff_v8b3n5q0w2e7h7d2k9m4x1c6",  "projectId": "proj_tz4a98xxat96iws9zmbrgj3a",  "key": "new-checkout",  "description": "The redesigned checkout screen.",  "type": "boolean",  "isEnabled": true,  "rolloutPercentage": 50,  "isArchived": false,  "experimentId": null,  "createdAt": "2026-02-24T10:12:45.000Z",  "updatedAt": "2026-04-21T08:00:00.000Z"}

{  "error": {    "type": "invalid_request",    "code": "string",    "message": "string",    "param": "string"  }}

{  "error": {    "type": "unauthenticated",    "code": "invalid_api_key",    "message": "This secret key is not valid."  }}

{  "error": {    "type": "permission_denied",    "code": "permission_denied",    "message": "Insufficient permissions."  }}

{  "error": {    "type": "not_found",    "code": "project_not_found",    "message": "There is no project proj_tz4a98xxat96iws9zmbrgj3a, or this credential cannot use it.",    "param": "projectId"  }}

{  "error": {    "type": "conflict",    "code": "feature_flag_managed_by_experiment",    "message": "Feature flag ff_k9m4x1c6v8b3n5q0w2e7h7d2 assigns the arms of experiment exp_c6v8b3n5q0w2e7h7d2k9m4x1; change it through the experiment."  }}

{  "error": {    "type": "internal",    "code": "internal_error",    "message": "Something went wrong on our side. Try again, and contact support with the Request-Id header if it keeps failing."  }}