feat(forms): per-member 'Forms submitted' view on the members page

listMemberSubmissions (forms.manage, RLS-honoring, metadata only) + a
FORMS column/button -> MemberFormsDialog listing the member's
submissions (title, kind, version, date) with a link to the audited
forms results surface. Gated by forms.manage (matches existing
submission-read RLS; no new exposure).

lib/validations.ts

@@ -673,6 +673,10 @@ export const linkSubmissionsSchema = z.object({
   email: emailField(),
 })
 
+export const memberSubmissionsSchema = z.object({
+  memberId: z.string().uuid('Invalid member ID'),
+})
+
 export const getPublicFormSchema = z.object({
   space: z.string().min(1).max(100),
   slug: formSlug,