A file lives exactly as long as something holds it

Deleting a post, editing media out, replacing an avatar or a header, and removing a whole root deleted no file: every
one stayed on disk and publicly served from /media/files with a year-long immutable cache, its row orphaned. Now every
upload is a row, profile pictures too (Kind avatar or header, ProfileOfAvatarId), and each of those acts trashes what
it held, as does an upload never posted for a day and a dropped scheduled post. A trashed row is marked in one
conditional update (an upload attached meanwhile is left alone), its files move into media-trash, beside the media
root and outside what /media/files serves, and the janitor deletes them a day later. Nothing is deleted for looking
unused.

Along the way: a profile picture that isn't an image, or can't be read, answers 422 instead of being silently ignored
with a 200; a removed root's scheduled posts are dropped, so nothing of it publishes later; media rows get indexes
(they had none), and the janitor's first pass comes five minutes after boot instead of an hour.

`PrivaPub admin media audit [--fix]` compares the disk with the database. With --fix (as www-data) it gives the
pictures personas show today a row, and trashes media of deleted posts or personas, rows whose files are missing, and
files nothing holds: the leftovers of every deletion until now. MediaLifecycleTests covers each act, that the trash is
never served, and the audit.

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

PrivaPub/Infrastructure/Data/Indexes.cs

@@ -32,6 +32,13 @@ namespace PrivaPub.Infrastructure.Data
 			await Plain<Post>(token, p => p.AnsweringToPostId);
 			await DB.Default.Index<Post>().Key(p => p.Geo, KeyType.Geo2DSphere).CreateAsync(token);
 
+			// media: a post's, a persona's, what a scheduled post holds, the janitor's never-posted uploads and its trash
+			await Plain<Models.Media.MediaAttachment>(token, m => m.PostId, m => m.ScheduledStatusId, m => m.CreatedAt);
+			await Plain<Models.Media.MediaAttachment>(token, m => m.OwnerAvatarId);
+			await Plain<Models.Media.MediaAttachment>(token, m => m.ScheduledStatusId);
+			await Plain<Models.Media.MediaAttachment>(token, m => m.ProfileOfAvatarId);
+			await Plain<Models.Media.MediaAttachment>(token, m => m.TrashedAt);
+
 			await Unique<DmPost>(p => p.ObjectURI, Builders<DmPost>.Filter.Gt(p => p.ObjectURI, ""), token);
 			await Plain<DmPost>(token, p => p.GroupId, p => p.ID);