test(app): studysets synced against a running server

The first tests that need serverpod start running (ADR 0001, rule 9: the client's and the server's sync engines can't share one process), tagged requires-server: tool/check.sh skips them, flutter test -t requires-server runs them. Every device is its own client and local database with the app's real gateway and repository, and syncs only when a test says so.

They state: two devices of one person end up with the same studysets; a deleted studyset leaves the other devices, and its payload is blank on the server, checked with SQL against the development database because the engine keeps deleted rows; a studyset written into another person's space never reaches them; claiming another person's space shows none of their studysets, since the server sends only the spaces the signed-in person has access to. As written here, the forgery test also expects the server to refuse and log the write, and the SQL checks connect over TCP; the first run against the server corrected both (see the commit "the sync tests pass against the running server").

They live in the app package: the server's Docker build resolves its dependencies with only the server package present, so a dev dependency on the client package would break it. They never initialize a Flutter test binding, which would replace real HTTP with a mock. Without a server they fail at sign-in with "connection refused".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/pubspec.yaml

@@ -51,6 +51,10 @@ dev_dependencies:
     sdk: flutter
   flutter_test:
     sdk: flutter
+  # The sync tests (test/sync/) sign in like the app and read the server's database.
+  postgres: ^3.5.16
+  serverpod_auth_core_client: 4.0.3
+  yaml: ^3.1.4
 
 dependency_overrides:
   flutter_secure_storage: ^10.0.0