feat: redesign superadmin agencies list, implement flat design, add date filters, and fix UI bugs

postgres/migrations/000_create_superadmin.sql

@@ -0,0 +1,3 @@
+INSERT INTO users (id, email, password_hash, role, is_active, created_at, updated_at) 
+VALUES (gen_random_uuid(), 'admin@aggios.app', '\\\', 'SUPERADMIN', true, NOW(), NOW()) 
+ON CONFLICT (email) DO UPDATE SET password_hash = '\\\';