Domain blocks: suspend, silence, reject media

DomainBlock (domain, severity, reject-media, public and private comment)
covers the domain and its subdomains. Admins manage them under
/clientapi/admin/domainblocks/{list,insert,delete}; the set is kept in
memory, reloaded on every change and at most five minutes stale.

A suspended domain is refused by FederationHttp.IsAllowed, so nothing is
fetched from it and no job delivers to it, and the inbox drops its
activities with a 202 before fetching any key. Reject-media strips the
attachments of posts from that domain. Silence is recorded for the
timelines and notifications that arrive in P1.2.

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

PrivaPub/Infrastructure/Http/FederationHttp.cs

@@ -1,6 +1,8 @@
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 
+using PrivaPub.Federation.Moderation;
+
 using System.Net;
 using System.Text.Json;
 
@@ -41,14 +43,16 @@ namespace PrivaPub.Infrastructure.Http
 		readonly IHttpClientFactory _httpClientFactory;
 		readonly IMemoryCache _cache;
 		readonly IOptionsMonitor<FederationOptions> _options;
+		readonly IDomainBlocks _domainBlocks;
 		readonly ILogger<FederationHttp> _logger;
 
 		public FederationHttp(IHttpClientFactory httpClientFactory, IMemoryCache cache, IOptionsMonitor<FederationOptions> options,
-			ILogger<FederationHttp> logger)
+			IDomainBlocks domainBlocks, ILogger<FederationHttp> logger)
 		{
 			_httpClientFactory = httpClientFactory;
 			_cache = cache;
 			_options = options;
+			_domainBlocks = domainBlocks;
 			_logger = logger;
 		}
 
@@ -56,6 +60,8 @@ namespace PrivaPub.Infrastructure.Http
 		{
 			if (target is not { IsAbsoluteUri: true } || !string.IsNullOrEmpty(target.UserInfo))
 				return false;
+			if (_domainBlocks?.IsSuspended(target.Host) == true)
+				return false;
 			var options = _options.CurrentValue;
 			if (target.Scheme != Uri.UriSchemeHttps && !(options.AllowPlainHttp && target.Scheme == Uri.UriSchemeHttp))
 				return false;