T1: tests stop sharing state they don't own

- JobQueue takes an optional scope, so a test's worker leases and reaps only its own jobs.
- The dead-host delivery test runs alone (Exclusive), on its own jobs, and cleans up the
  breaker rows it trips; the breaker has tests of its own on unique hosts.
- Index and migration tests run alone: they drop indexes and rewrite every post.
- DomainBlocks.Load replaces reflection and a database-wide block in tests.
- Harness.Outgoing sees only deliveries queued since the harness started: Peer ports are
  reused within a run, which made the circle test flaky.
- Two pure-logic tests leave Mongo-gated classes, so CI runs them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ELjqpznMFMNrJoJUj6K5p2

PrivaPub.Tests/Federation/DomainBlocksTests.cs

@@ -0,0 +1,37 @@
+using Microsoft.Extensions.Logging.Abstractions;
+
+using PrivaPub.Federation.Moderation;
+using PrivaPub.Models.Federation;
+
+namespace PrivaPub.Tests.Federation
+{
+	public class DomainBlocksTests
+	{
+		[Fact]
+		public void A_block_covers_subdomains_but_not_lookalikes()
+		{
+			var blocks = new DomainBlocks(NullLogger<DomainBlocks>.Instance);
+			blocks.Load(new[] { new DomainBlock { Domain = "evil.example", Severity = DomainBlockSeverity.Silence } });
+
+			Assert.NotNull(blocks.Find("evil.example"));
+			Assert.NotNull(blocks.Find("A.Evil.Example."));
+			Assert.Null(blocks.Find("notevil.example"));
+			Assert.False(blocks.IsSuspended("evil.example"));
+		}
+
+		[Fact]
+		public void A_suspension_is_found_from_any_subdomain()
+		{
+			var blocks = new DomainBlocks(NullLogger<DomainBlocks>.Instance);
+			blocks.Load(new[]
+			{
+				new DomainBlock { Domain = " Spam.Example. ", Severity = DomainBlockSeverity.Suspend },
+				new DomainBlock { Domain = "", Severity = DomainBlockSeverity.Suspend }
+			});
+
+			Assert.True(blocks.IsSuspended("deep.inside.spam.example"));
+			Assert.False(blocks.IsSuspended("example"));
+			Assert.Null(blocks.Find(default));
+		}
+	}
+}