Scheduled posts: written now, published at their time

POST /api/v1/statuses with scheduled_at no longer posts at once: the post is
kept as asked (at least five minutes ahead; 300 waiting, 25 a day, as
Mastodon allows), its media kept from the janitor, and a PublishScheduled job
publishes it at its time as the persona. scheduled_statuses lists, moves and
drops them; a moved post's old job finds it not due. Idempotency-Key holds
for scheduling too.

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

PrivaPub.Tests/Http/MastodonInstanceTests.cs

@@ -84,7 +84,6 @@ namespace PrivaPub.Tests.Http
 		[InlineData("/api/v1/followed_tags")]
 		[InlineData("/api/v1/endorsements")]
 		[InlineData("/api/v1/featured_tags")]
-		[InlineData("/api/v1/scheduled_statuses")]
 		public async Task Signed_in_stub_routes_answer_empty_lists(string path)
 		{
 			var reader = await _host.Mastodon("reader");