fix(comments): handle tombstones that omit author and record entirely master
The backend now omits the `author` and `record` fields entirely on deleted-comment tombstones (older backends sent `record: null` and a real DID with an empty handle). Rendering code that assumed a present author would crash on the missing field or de-anonymize the deleted comment's author. Follow-up to e94a51dd. Changes: - Make `CommentView.record` and `CommentView.author` optional in the Coves API types, with doc comments describing the tombstone shape - Comment.svelte: show the deleted-author placeholder when `author` is absent (not only when `isDeleted`), and use `author?.did` for the OP-badge check - CommentActions.svelte: use `comment.author?.did` in the edit/delete identity checks so tombstones don't throw (and correctly hide those actions when there is no author to match) - Profile page: guard the comment UserLink behind `{#if comment.author}` with the deleted-author placeholder as fallback - Add a buildCommentsTree test for tombstones with both keys absent, and align the existing undefined-record test with the new types Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>