refactor(actions): split classes.ts into a folder (slice 3)

908-line lib/actions/classes.ts → lib/actions/classes/{definitions,sessions,
signups,instructor}.ts ('use server') + _guard.ts (requirePermission/Gate) +
_forms.ts (findSpaceForm/hasFormSubmission) + a plain index.ts barrel. All 14
actions preserved verbatim; lib/actions/index.ts unchanged. Helpers stay
internal (not re-exported). tsc 0, tests green.

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

lib/actions/classes/_forms.ts

@@ -0,0 +1,40 @@
+import { createAdminClient } from '@/lib/supabase/admin'
+
+// A class manager need not hold forms.manage, so form lookups + the
+// submission gate use the service client (scoped by space_id) and never
+// return form answers -- only existence/metadata.
+export async function findSpaceForm(
+  admin: ReturnType<typeof createAdminClient>,
+  spaceId: string,
+  formId: string,
+): Promise<{ id: string; status: string; title: string; slug: string } | null> {
+  const { data } = await admin
+    .from('forms')
+    .select('id, status, title, slug')
+    .eq('id', formId)
+    .eq('space_id', spaceId)
+    .maybeSingle()
+  return data
+    ? {
+        id: data.id as string,
+        status: data.status as string,
+        title: data.title as string,
+        slug: data.slug as string,
+      }
+    : null
+}
+
+export async function hasFormSubmission(
+  admin: ReturnType<typeof createAdminClient>,
+  spaceId: string,
+  memberId: string,
+  formId: string,
+): Promise<boolean> {
+  const { count } = await admin
+    .from('form_submissions')
+    .select('id', { count: 'exact', head: true })
+    .eq('space_id', spaceId)
+    .eq('form_id', formId)
+    .eq('member_id', memberId)
+  return (count ?? 0) > 0
+}