feat(schema): add is_super_user to staff table (GRO-201)

Add boolean is_super_user column (default false) to staff table.
Update Staff interface in shared types.
Mark first manager as super user in both seed modes.
Update test fixtures to include isSuperUser field.

Co-authored-by: groombook-ci[bot] <ci@groombook.bot>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/__tests__/groomerIsolation.test.ts

@@ -17,6 +17,7 @@ const MANAGER: StaffRow = {
   oidcSub: "oidc-manager-sub",
   userId: null,
   role: "manager",
+  isSuperUser: true,
   name: "Manager McManager",
   email: "manager@example.com",
   active: true,

apps/api/src/__tests__/petPhotos.test.ts

@@ -9,6 +9,7 @@ const MANAGER: StaffRow = {
   oidcSub: "oidc-manager-sub",
   userId: null,
   role: "manager",
+  isSuperUser: true,
   name: "Manager McManager",
   email: "manager@example.com",
   active: true,

apps/api/src/__tests__/rbac.test.ts

@@ -10,6 +10,7 @@ const MANAGER: StaffRow = {
   oidcSub: "oidc-manager-sub",
   userId: "ba-user-manager",
   role: "manager",
+  isSuperUser: true,
   name: "Manager McManager",
   email: "manager@example.com",
   active: true,