A status asked for by id is shown, and remote warnings are their own

GET /api/v1/statuses/:id applied the viewer's own blocks and mutes and
answered 200 with null for a post of an author the viewer had blocked;
decePub's thread page then showed nothing. As in Mastodon, a status asked
for by id (or acted on) is shown whatever the viewer blocked or muted,
and only lists leave such posts out; when nothing can be shown the
answer is 404, never null, and search leaves it out.

A remote post marked sensitive with an empty summary (Akkoma's sensitive
media, Lemmy's NSFW) got an invented "Content warning" that hid its
words. A remote post now keeps its own summary: sensitive without one
hides the media only. A local post warned without words still gets the
default warning.

Both found by decePub's end-to-end tests on the town.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub/Api/Mastodon/Controllers/StatusesController.cs

@@ -92,7 +92,8 @@ namespace PrivaPub.Api.Mastodon.Controllers
 		public async Task<IActionResult> Get(string id, CancellationToken token)
 		{
 			var post = await Visible(id, token);
-			return post == default ? NotFoundError() : Json(await _mapper.Status(post, MyId, token));
+			var status = post == default ? default : await _mapper.Status(post, MyId, token);
+			return status == default ? NotFoundError() : Json(status);
 		}
 
 		[HttpPut("/api/v1/statuses/{id}"), Scope("write:statuses")]
@@ -364,7 +365,8 @@ namespace PrivaPub.Api.Mastodon.Controllers
 		async Task<IActionResult> Unchanged(string id, CancellationToken token)
 		{
 			var post = await Visible(id, token);
-			return post == default ? NotFoundError() : Json(await _mapper.Status(post, MyId, token));
+			var status = post == default ? default : await _mapper.Status(post, MyId, token);
+			return status == default ? NotFoundError() : Json(status);
 		}
 
 		async Task<PostEntity> Visible(string id, CancellationToken token)