Accepts Vec<i64> of comment IDs, returns their current status.
IDs not found in DB return status 'gone'. Empty vec returns early.
Used by client to prune localStorage pending comments that are
no longer pending (approved/spam/trash/deleted).
- Add comment_id/avatar_url/depth Option fields to CommentResponse with serde default
- Extract RETURNING id from INSERT in create.rs
- Compute gravatar_url server-side (md5 not available in WASM)
- Return computed depth for correct client-side pending comment indentation
- All error paths return None for all new fields
