test(triggers): mirror the app_id-not-null inbound guard in the mock (review)

Adversarial review NIT: the #[cfg(test)] InMemoryTriggerRepo's
email_inbound_target `.expect()`s app_id, which would panic if a future
unit test fetched a group-owned email TEMPLATE. Filter `app_id.is_some()`
like the production query's `AND t.app_id IS NOT NULL` so the mock stays
faithful. Test-only; no production change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/manager-core/src/triggers_api.rs

@@ -1027,9 +1027,12 @@ mod tests {
         ) -> Result<Option<EmailInboundTarget>, TriggerRepoError> {
             let g = self.inner.lock().await;
             Ok(g.get(&trigger_id)
-                .filter(|t| t.kind == TriggerKind::Email)
+                // Mirror the production guard (`email_inbound_target` filters
+                // `AND t.app_id IS NOT NULL`): a group-owned email TEMPLATE is
+                // never a valid inbound target.
+                .filter(|t| t.kind == TriggerKind::Email && t.app_id.is_some())
                 .map(|t| EmailInboundTarget {
-                    app_id: t.app_id.expect("email trigger is app-owned"),
+                    app_id: t.app_id.expect("filtered to app-owned above"),
                     script_id: t.script_id,
                     enabled: t.enabled,
                     dispatch_mode: t.dispatch_mode,