fix(projects): disable create while the team selection is invalid

The inline at-least-one-team hint showed red while the Create button
stayed clickable (toast on click). Invalid state now disables the button,
matching the empty-title condition; the submit-time toast stays as the
server-rule backstop.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/views/modals/create-project.tsx

@@ -881,7 +881,7 @@ export function CreateProjectModal({ onClose }: { onClose: () => void }) {
           <Button
             size="sm"
             onClick={handleSubmit}
-            disabled={!title.trim() || submitting}
+            disabled={!title.trim() || submitting || (teams.length > 0 && teamIds.length === 0)}
             className="shrink-0"
           >
             {submitting ? t(($) => $.create_project.submitting) : t(($) => $.create_project.submit)}