调现金弹窗:目标账户选择 + 四项必填校验 + 邀请余额展示 (#30)

- 新增「目标账户」单选(金币兑现金账户 / 邀请账户),默认不选、必选
- 操作方式改为必选无默认(原默认「增减」),进来需手动选
- 四项(目标账户/操作方式/现金变动/原因)全部必填必选:标题带红星 *,
  点确定时缺项 → 字段下方红字报错并阻断提交
- 提交携带 account;弹窗顶部余额行加显「邀请奖励金」(UserOverview 新字段)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: zzhyyyyy <2685922758@qq.com>
Reviewed-on: #30
Co-authored-by: zhuzihao <zhuzihao@wonderable.ai>
Co-committed-by: zhuzihao <zhuzihao@wonderable.ai>

src/lib/types.ts

@@ -81,6 +81,7 @@ export interface UserOverview {
   user: UserListItem;
   coin_balance: number;
   cash_balance_cents: number;
+  invite_cash_balance_cents: number; // 邀请奖励金余额(与 cash_balance_cents 物理隔离)
   total_coin_earned: number;
   comparison_total: number;
   comparison_success: number;