T3: the whole server under test

PrivaPubHost is a WebApplicationFactory<Program> on the fixture's database, configured only
through UseSetting (visible before Build, unlike ConfigureAppConfiguration). It drops the
background workers so tests run the jobs they queue (Jobs.Run, RunInbox), gives each client
its own address for the rate limiter, and has a SecureMode variant. Accounts signs up roots,
adds personas and gets Mastodon tokens through the real /oauth code flow. RemoteActor signs
HttpRequestMessages for the real /peasants routes; Peer records bodies and headers and
serves files with ranges and text pages.

Program registers the Guid serializer with TryRegisterSerializer, so a second host in one
process starts; the fixture runs the migrations in production's order before any test.

HostBootTests: the host shares the fixture database; the harness handles exactly the
activities the server registers; every job kind has one handler; every controller and page
model can be made; the service graph validates with ValidateOnBuild and ValidateScopes;
Swagger is 404 outside Development; a persona's token never names its root; a signed DM
through the real /mouth route is queued, processed and stored.

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

PrivaPub.Tests/Support/MongoFixture.cs

@@ -41,6 +41,7 @@ namespace PrivaPub.Tests.Support
 			await DB.InitAsync(Database, settings);
 			await RefuseProductionData();
 			EntityMaps.Warm();
+			await DB.Default.MigrateAsync<Program>();
 			await Indexes.Create();
 		}