💱 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.

logger/logger.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"log"
 	"one-api/common"
+	"one-api/setting/operation_setting"
 	"os"
 	"path/filepath"
 	"sync"
@@ -92,18 +93,55 @@ func logHelper(ctx context.Context, level string, msg string) {
 }
 
 func LogQuota(quota int) string {
-	if common.DisplayInCurrencyEnabled {
-		return fmt.Sprintf("＄%.6f 额度", float64(quota)/common.QuotaPerUnit)
-	} else {
+	// 新逻辑：根据额度展示类型输出
+	q := float64(quota)
+	switch operation_setting.GetQuotaDisplayType() {
+	case operation_setting.QuotaDisplayTypeCNY:
+		usd := q / common.QuotaPerUnit
+		cny := usd * operation_setting.USDExchangeRate
+		return fmt.Sprintf("¥%.6f 额度", cny)
+	case operation_setting.QuotaDisplayTypeCustom:
+		usd := q / common.QuotaPerUnit
+		rate := operation_setting.GetGeneralSetting().CustomCurrencyExchangeRate
+		symbol := operation_setting.GetGeneralSetting().CustomCurrencySymbol
+		if symbol == "" {
+			symbol = "¤"
+		}
+		if rate <= 0 {
+			rate = 1
+		}
+		v := usd * rate
+		return fmt.Sprintf("%s%.6f 额度", symbol, v)
+	case operation_setting.QuotaDisplayTypeTokens:
 		return fmt.Sprintf("%d 点额度", quota)
+	default: // USD
+		return fmt.Sprintf("＄%.6f 额度", q/common.QuotaPerUnit)
 	}
 }
 
 func FormatQuota(quota int) string {
-	if common.DisplayInCurrencyEnabled {
-		return fmt.Sprintf("＄%.6f", float64(quota)/common.QuotaPerUnit)
-	} else {
+	q := float64(quota)
+	switch operation_setting.GetQuotaDisplayType() {
+	case operation_setting.QuotaDisplayTypeCNY:
+		usd := q / common.QuotaPerUnit
+		cny := usd * operation_setting.USDExchangeRate
+		return fmt.Sprintf("¥%.6f", cny)
+	case operation_setting.QuotaDisplayTypeCustom:
+		usd := q / common.QuotaPerUnit
+		rate := operation_setting.GetGeneralSetting().CustomCurrencyExchangeRate
+		symbol := operation_setting.GetGeneralSetting().CustomCurrencySymbol
+		if symbol == "" {
+			symbol = "¤"
+		}
+		if rate <= 0 {
+			rate = 1
+		}
+		v := usd * rate
+		return fmt.Sprintf("%s%.6f", symbol, v)
+	case operation_setting.QuotaDisplayTypeTokens:
 		return fmt.Sprintf("%d", quota)
+	default:
+		return fmt.Sprintf("＄%.6f", q/common.QuotaPerUnit)
 	}
 }