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

CLAUDE.md

@@ -333,6 +333,12 @@ mongod fails the run instead of silently skipping half the tests.
 - `Support/Peer` is an in-process HTTP server answering on two origins (`127.0.0.1` and `localhost`), so origin rules
   can be tested; `Support/RemoteActor` signs real deliveries with its own key.
 - Inbox scenarios go through `InboxReceiver.Receive` with a signed request, not through the private handlers.
+- `Support/Host/PrivaPubHost` is the whole server under test (`WebApplicationFactory<Program>`, environment `Testing`,
+  configured only through `UseSetting`, on the fixture's database). `PrivaPubHost.Shared()` boots it once per run;
+  `SecureModeHost` is the same with `Federation:SecureMode`. Background workers are removed, so a test runs the jobs it
+  queued with `host.Run(j => ...)` or `host.RunInbox(activityId)`. `Accounts` signs a root up, adds personas, and gets a
+  Mastodon token through the real `/oauth` code flow; `RemoteActor.SignedPost`/`SignedGet` sign `HttpRequestMessage`s
+  for the real `/peasants` routes. Each client gets its own `X-Test-Client` address, so rate limits don't collide.
 - All test classes share one database and run in parallel, so a test touches only rows it made:
   - random names and GUIDs;
   - `Harness.Outgoing` sees only deliveries queued since that harness started, because Peer ports are reused;