docs: explain stylesheet ownership, responsive rules and display boundaries

app/assets/styles/GeetestField.DiieTibK.css

@@ -1,3 +1,5 @@
+/* 极验入口：验证码触发按钮的可见状态。 */
+/* 导入方：app/components/CaptchaField.vue、app/components/GeetestField.vue、app/components/SecurityVerificationDialog.vue、app/components/instance/DcimActions.vue、app/components/instance/DcimBilling.vue、app/components/instance/DcimManage.vue、app/components/instance/InstanceAccess.vue、app/components/instance/InstanceBilling.vue、app/components/instance/InstanceSmsCode.vue、app/pages/account/index.vue、app/pages/forgot-password.vue、app/pages/login.vue、app/pages/oauth/bind.vue、app/pages/register.vue、app/pages/transfer/index.vue。 */
 .geetest-field[data-v-4cd14cdc] {
   flex-direction: column;
   gap: 8px;
@@ -21,6 +23,7 @@
 .geetest-trigger[data-v-4cd14cdc]:hover:not(:disabled) {
   border-color: var(--p-primary-color);
 }
+/* 键盘操作的可见焦点：不要只保留鼠标 hover 效果而移除此反馈。 */
 .geetest-trigger[data-v-4cd14cdc]:focus-visible {
   outline: 2px solid var(--p-primary-color);
   outline-offset: 2px;