R8 the Mastodon API made real in decePub: featured tags, notify, languages, recommendations, notes, suggestions, the direct stream

A profile shows the hashtags an account features as chips opening their feed; under another account's header is what the
persona keeps of it for itself alone: for one it follows, a bell (follow with notify), the languages of its posts that
reach the home feed (follow with languages[]) and Recommend (endorsements, private here), and for any account a private
note saved on blur or with Save. Settings edits the persona's featured hashtags (added by name or from those used lately,
10 at most) and its reading preferences (/clientapi/avatar/private/preferences), which CascadingState keeps per persona
and the card applies to sensitive media and content warnings. A hashtag's tab features it on the profile. Explore has Who
to follow (/api/v2/suggestions, dismissed for good after asking); Administration has Staff picks. The Direct tab follows
the direct stream's conversation events; status notifications show the post. The follows CSV carries notify and languages.

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

Components/Feed/FeedTabs.razor

@@ -2,7 +2,8 @@
 
 @* The feed page's tabs, one per kind of feed, scrolling sideways on narrow screens. Groups adds a choice of the
    persona's communities and circles, Lists a choice of its lists (made and filled on /lists), Tag the hashtag being
-   read, with its week and a button to follow it (its public posts then come home). The stats icon shows how the current feed was
+   read, with its week, a button to follow it (its public posts then come home) and one to feature it on the persona's
+   profile (public: its followers are told). The stats icon shows how the current feed was
    read; the buttons on the right open the composer and, on narrow screens, the globe. *@
 <div class="flex flex-col gap-2">
 	<div class="flex items-center gap-2 min-w-0">
@@ -99,6 +100,15 @@
 						 OnClick="ToggleTagFollow" data-tag-follow>
 					<span>@(tag.Following == true ? Localizer["Stop following #{0}", tag.Name] : Localizer["Follow #{0}", tag.Name])</span>
 				</DButton>
+				@if (tag.Featuring is { } featuring)
+				{
+					<DButton Size="DSize.Xs" Active="featuring" Disabled="@(IsDefaultDisabled || isFollowing)" OnClick="ToggleTagFeature"
+							 title="@Localizer["Featured hashtags are public: they show on the persona's profile, and its followers are told."]"
+							 aria-pressed="@(featuring ? "true" : "false")" data-tag-feature="@(featuring ? "on" : "off")">
+						<i class="ion-md-ribbon" aria-hidden="true"></i>
+						<span>@(featuring ? Localizer["Featured on profile"] : Localizer["Feature on profile"])</span>
+					</DButton>
+				}
 			}
 		</div>
 	}
@@ -176,6 +186,21 @@
 		Toast.AddResponseSuccess(tag.Following == true ? Localizer["Following #{0}: its public posts come home.", tag.Name] : Localizer["No longer following #{0}.", tag.Name]);
 	}
 
+	async Task ToggleTagFeature()
+	{
+		isFollowing = true;
+		var result = await DiscoveryService.FeatureTag(tag.Name, tag.Featuring != true);
+		isFollowing = false;
+		if (result.IsInvalid)
+		{
+			Toast.AddResponseError(result);
+			return;
+		}
+
+		tag = (Tag)result.Data;
+		Toast.AddResponseSuccess(tag.Featuring == true ? Localizer["#{0} is featured on this persona's profile.", tag.Name] : Localizer["#{0} is no longer featured.", tag.Name]);
+	}
+
 	string TabName(TimelineType type) => type switch
 	{
 		TimelineType.Federation => Localizer["Federated"],