💱 feat(settings): introduce site-wide quota display type (USD/CNY/TOKENS/CUSTOM)

Replace the legacy boolean “DisplayInCurrencyEnabled” with an injected, type-safe
configuration `general_setting.quota_display_type`, and wire it through the
backend and frontend.

Backend
- Add `QuotaDisplayType` to `operation_setting.GeneralSetting` with injected
  registration via `config.GlobalConfig.Register("general_setting", ...)`.
  Helpers: `IsCurrencyDisplay()`, `IsCNYDisplay()`, `GetQuotaDisplayType()`.
- Expose `quota_display_type` in `/api/status` and keep legacy
  `display_in_currency` for backward compatibility.
- Logger: update `LogQuota` and `FormatQuota` to support USD/CNY/TOKENS. When
  CNY is selected, convert using `operation_setting.USDExchangeRate`.
- Controllers:
  - `billing`: compute subscription/usage amounts based on the selected type
    (USD: divide by `QuotaPerUnit`; CNY: USD→CNY; TOKENS: keep raw tokens).
  - `topup` / `topup_stripe`: treat inputs as “amount” for USD/CNY and as
    token-count for TOKENS; adjust min topup and pay money accordingly.
  - `misc`: include `quota_display_type` in status payload.
- Compatibility: in `model/option.UpdateOption`, map updates to
  `DisplayInCurrencyEnabled` → `general_setting.quota_display_type`
  (true→USD, false→TOKENS). Keep exporting the legacy key in `OptionMap`.

Frontend
- Settings: replace the “display in currency” switch with a Select
  (`general_setting.quota_display_type`) offering USD / CNY / Tokens.
  Provide fallback mapping from legacy `DisplayInCurrencyEnabled`.
- Persist `quota_display_type` to localStorage (keep `display_in_currency`
  for legacy components).
- Rendering helpers: base all quota/price rendering on `quota_display_type`;
  use `usd_exchange_rate` for CNY symbol/values.
- Pricing page: default view currency follows site display type (USD/CNY),
  while TOKENS mode still allows per-view currency toggling when needed.

Notes
- No database migrations required.
- Legacy clients remain functional via compatibility fields.

web/src/pages/Setting/Payment/SettingsPaymentGateway.jsx

@@ -118,14 +118,20 @@ export default function SettingsPaymentGateway(props) {
       }
     }
 
-    if (originInputs['AmountOptions'] !== inputs.AmountOptions && inputs.AmountOptions.trim() !== '') {
+    if (
+      originInputs['AmountOptions'] !== inputs.AmountOptions &&
+      inputs.AmountOptions.trim() !== ''
+    ) {
       if (!verifyJSON(inputs.AmountOptions)) {
         showError(t('自定义充值数量选项不是合法的 JSON 数组'));
         return;
       }
     }
 
-    if (originInputs['AmountDiscount'] !== inputs.AmountDiscount && inputs.AmountDiscount.trim() !== '') {
+    if (
+      originInputs['AmountDiscount'] !== inputs.AmountDiscount &&
+      inputs.AmountDiscount.trim() !== ''
+    ) {
       if (!verifyJSON(inputs.AmountDiscount)) {
         showError(t('充值金额折扣配置不是合法的 JSON 对象'));
         return;
@@ -163,10 +169,16 @@ export default function SettingsPaymentGateway(props) {
         options.push({ key: 'PayMethods', value: inputs.PayMethods });
       }
       if (originInputs['AmountOptions'] !== inputs.AmountOptions) {
-        options.push({ key: 'payment_setting.amount_options', value: inputs.AmountOptions });
+        options.push({
+          key: 'payment_setting.amount_options',
+          value: inputs.AmountOptions,
+        });
       }
       if (originInputs['AmountDiscount'] !== inputs.AmountDiscount) {
-        options.push({ key: 'payment_setting.amount_discount', value: inputs.AmountDiscount });
+        options.push({
+          key: 'payment_setting.amount_discount',
+          value: inputs.AmountDiscount,
+        });
       }
 
       // 发送请求
@@ -273,7 +285,7 @@ export default function SettingsPaymentGateway(props) {
             placeholder={t('为一个 JSON 文本')}
             autosize
           />
-          
+
           <Row
             gutter={{ xs: 8, sm: 16, md: 24, lg: 24, xl: 24, xxl: 24 }}
             style={{ marginTop: 16 }}
@@ -282,13 +294,17 @@ export default function SettingsPaymentGateway(props) {
               <Form.TextArea
                 field='AmountOptions'
                 label={t('自定义充值数量选项')}
-                placeholder={t('为一个 JSON 数组，例如：[10, 20, 50, 100, 200, 500]')}
+                placeholder={t(
+                  '为一个 JSON 数组，例如：[10, 20, 50, 100, 200, 500]',
+                )}
                 autosize
-                extraText={t('设置用户可选择的充值数量选项，例如：[10, 20, 50, 100, 200, 500]')}
+                extraText={t(
+                  '设置用户可选择的充值数量选项，例如：[10, 20, 50, 100, 200, 500]',
+                )}
               />
             </Col>
           </Row>
-          
+
           <Row
             gutter={{ xs: 8, sm: 16, md: 24, lg: 24, xl: 24, xxl: 24 }}
             style={{ marginTop: 16 }}
@@ -297,13 +313,17 @@ export default function SettingsPaymentGateway(props) {
               <Form.TextArea
                 field='AmountDiscount'
                 label={t('充值金额折扣配置')}
-                placeholder={t('为一个 JSON 对象，例如：{"100": 0.95, "200": 0.9, "500": 0.85}')}
+                placeholder={t(
+                  '为一个 JSON 对象，例如：{"100": 0.95, "200": 0.9, "500": 0.85}',
+                )}
                 autosize
-                extraText={t('设置不同充值金额对应的折扣，键为充值金额，值为折扣率，例如：{"100": 0.95, "200": 0.9, "500": 0.85}')}
+                extraText={t(
+                  '设置不同充值金额对应的折扣，键为充值金额，值为折扣率，例如：{"100": 0.95, "200": 0.9, "500": 0.85}',
+                )}
               />
             </Col>
           </Row>
-          
+
           <Button onClick={submitPayAddress}>{t('更新支付设置')}</Button>
         </Form.Section>
       </Form>