R7 custom emoji in decePub: the server's own, administered, picked, suggested and shown

Administration has a Custom emoji section (EmojiPanel, data-admin-section=emoji): the server's emoji by category, added
with a picture streamed from the file, changed (category, picker, disabled, picture; never the shortcode) and deleted,
asked first, with PrivaPub's 409 and 422 in the dialog. EmojiService reads /clientapi/admin/emoji and, for everyone,
/api/v1/custom_emojis, kept a day in localStorage (CustomEmojiCache) and read again after a change here. EmojiPicker
(a DDropdown sheet on a phone, rendered only while open) offers them by category with common unicode emoji, searchable:
the composer writes the choice at the caret, a card and the announcements banner react with it. The composer suggests
custom emoji after `:` and two letters. Custom reactions toggle as :shortcode: and show their picture, notifications of
one too; located posts, announcements and NavMenu's persona names render the server's emoji.

Verified: Release build, 0 errors (the 3 warnings were there before). Not run against PrivaPub or in the pasture.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WpVCoDeM1qUTRp4fXQdfof

Models/Mastodon/Account.cs

@@ -73,11 +73,15 @@ public class AccountField
 	public DateTime? VerifiedAt { get; set; }
 }
 
+/// <summary>A custom emoji: one a post or an account names (its server's), or one of this server's own as
+/// /api/v1/custom_emojis lists them for the picker, with its category.</summary>
 public class CustomEmoji
 {
 	public string Shortcode { get; set; }
 	public string Url { get; set; }
 	public string StaticUrl { get; set; }
+	public bool VisibleInPicker { get; set; }
+	public string Category { get; set; }
 }
 
 public class Relationship