feat(account): keep complaints on deletion, clear their typed-in contact; say so in the privacy draft

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE

frontend/tests/account-deletion.test.tsx

@@ -53,6 +53,9 @@ test("the kept tables in code and in SQL are the same list, and finance is kept"
   const sqlList = migration.slice(migration.indexOf("select array["), migration.indexOf("]::text[]"));
   const sqlTables = [...sqlList.matchAll(/'([a-z_]+)'/g)].map((match) => match[1]);
   assert.deepEqual(sqlTables, [...ACCOUNT_DELETION_KEPT_TABLES]);
+  // 2026-09-30 合并时加入：反馈与投诉保留（产品决定），联系方式在清除时置空。
+  assert.match(migration, /'user_feedback'/);
+  assert.match(migration, /update public\.user_feedback set contact = null/);
   for (const table of ["payment_orders", "credit_transactions", "usage_ledger", "usage_reservations", "user_subscriptions", "birth_time_rectification_billing"]) {
     assert.ok((ACCOUNT_DELETION_KEPT_TABLES as readonly string[]).includes(table), table);
   }