P6: custom emoji, fuller remote profiles, and polls both ways

- Custom emoji (Emoji tags) on posts, display names, bios and profile fields, at most 64 per object, proxied, in
  Status.emojis and Account.emojis.
- Remote profiles keep their header, profile fields, locked flag, published date, movedTo, indexable, memorial and
  image descriptions (a locked GoToSocial account no longer shows as open).
- Polls: incoming Questions (Mastodon, Misskey, Pleroma, GoToSocial shapes) with counts, voters, end and closed;
  our own polls from the Mastodon API go out as Questions; votes in are counted once per voter and never become
  replies; personas vote on other servers' polls with one Note per choice; counts refresh with an Update at most every
  three minutes; a poll closes on time and tells its voters and its author. GET /api/v1/polls/:id and POST
  /api/v1/polls/:id/votes.
- An Update without a newer `updated` only refreshes poll, video, audio and event details and leaves no revision.

Checked live against GoToSocial: each side's poll reaches the other as a poll and each side's vote is counted.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub/Models/Post/Post.cs

@@ -25,6 +25,7 @@ namespace PrivaPub.Models.Post
 		public List<PostMention> Mentions { get; set; } = new();
 		public List<string> Tags { get; set; } = new();
 		public List<PostMedia> Media { get; set; } = new();
+		public List<CustomEmoji> Emojis { get; set; } = new();
 		[BsonIgnoreIfNull]
 		public PostSource Source { get; set; }//the remote author's own text (Markdown, MFM, BBCode)
 		[BsonIgnoreIfNull]
@@ -37,6 +38,8 @@ namespace PrivaPub.Models.Post
 		public AudioDetails Audio { get; set; }
 		[BsonIgnoreIfNull]
 		public EventDetails Event { get; set; }
+		[BsonIgnoreIfNull]
+		public PostPoll Poll { get; set; }
 		public List<float> Location { get; set; } = new();
 		public float RangeKm { get; set; } = 5.0f;
 		[BsonIgnoreIfNull]