💱 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.

relay/channel/ollama/dto.go

@@ -5,12 +5,12 @@ import (
 )
 
 type OllamaChatMessage struct {
-	Role      string            `json:"role"`
-	Content   string            `json:"content,omitempty"`
-	Images    []string          `json:"images,omitempty"`
-	ToolCalls []OllamaToolCall  `json:"tool_calls,omitempty"`
-	ToolName  string            `json:"tool_name,omitempty"`
-	Thinking  json.RawMessage   `json:"thinking,omitempty"`
+	Role      string           `json:"role"`
+	Content   string           `json:"content,omitempty"`
+	Images    []string         `json:"images,omitempty"`
+	ToolCalls []OllamaToolCall `json:"tool_calls,omitempty"`
+	ToolName  string           `json:"tool_name,omitempty"`
+	Thinking  json.RawMessage  `json:"thinking,omitempty"`
 }
 
 type OllamaToolFunction struct {
@@ -20,7 +20,7 @@ type OllamaToolFunction struct {
 }
 
 type OllamaTool struct {
-	Type     string            `json:"type"`
+	Type     string             `json:"type"`
 	Function OllamaToolFunction `json:"function"`
 }
 
@@ -43,28 +43,27 @@ type OllamaChatRequest struct {
 }
 
 type OllamaGenerateRequest struct {
-	Model     string         `json:"model"`
-	Prompt    string         `json:"prompt,omitempty"`
-	Suffix    string         `json:"suffix,omitempty"`
-	Images    []string       `json:"images,omitempty"`
-	Format    interface{}    `json:"format,omitempty"`
-	Stream    bool           `json:"stream,omitempty"`
-	Options   map[string]any `json:"options,omitempty"`
-	KeepAlive interface{}    `json:"keep_alive,omitempty"`
+	Model     string          `json:"model"`
+	Prompt    string          `json:"prompt,omitempty"`
+	Suffix    string          `json:"suffix,omitempty"`
+	Images    []string        `json:"images,omitempty"`
+	Format    interface{}     `json:"format,omitempty"`
+	Stream    bool            `json:"stream,omitempty"`
+	Options   map[string]any  `json:"options,omitempty"`
+	KeepAlive interface{}     `json:"keep_alive,omitempty"`
 	Think     json.RawMessage `json:"think,omitempty"`
 }
 
 type OllamaEmbeddingRequest struct {
-	Model     string         `json:"model"`
-	Input     interface{}    `json:"input"`
-	Options   map[string]any `json:"options,omitempty"`
+	Model      string         `json:"model"`
+	Input      interface{}    `json:"input"`
+	Options    map[string]any `json:"options,omitempty"`
 	Dimensions int            `json:"dimensions,omitempty"`
 }
 
 type OllamaEmbeddingResponse struct {
-	Error           string        `json:"error,omitempty"`
-	Model           string        `json:"model"`
-	Embeddings      [][]float64   `json:"embeddings"`
-	PromptEvalCount int           `json:"prompt_eval_count,omitempty"`
+	Error           string      `json:"error,omitempty"`
+	Model           string      `json:"model"`
+	Embeddings      [][]float64 `json:"embeddings"`
+	PromptEvalCount int         `json:"prompt_eval_count,omitempty"`
 }
-