M12e: contract pass (pair invite kind, admin name in invite links, sync failed flag, rejection actor, device version name, template id, update check result, untouched accounts, D-027 re-stamp, PushEvent in :core:model, snackbar hosts)

Server: E-3 invite_kind; E-12 link ?from=<admin name>, E-4 passes it into kvitt://invite;
X-Kvitt-App-Version-Name stored in devices.app_version_name (migration 0003, schema 3);
OpenAPI and examples follow. Phone: :core:model, :core:fakes, :data, features and :app
updated together; goldens re-recorded for S-20 (version name) and new S-1/S-22 states.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

server/crates/kvitt-server/tests/skeleton/support.rs

@@ -71,6 +71,11 @@ impl TestApp {
         Self::migrated_to(Some(1)).await
     }
 
+    /// A database migrated to schema 2 only (before 0003).
+    pub async fn at_v2() -> Self {
+        Self::migrated_to(Some(2)).await
+    }
+
     async fn migrated_to(target: Option<i64>) -> Self {
         let dir = TempDir::new();
         let config = Config::from_lookup(|k| {