feat: improve model price error UX with role-aware messages and cleaner UI

- Backend: differentiate error messages for admin vs regular users in price.go
- Backend: include error_code in channel test response for structured error handling
- Frontend: render model_price_error as a styled card in Playground with admin nav button
- Frontend: show inline error details and settings link in channel test modal
- Frontend: parse error codes from both SSE and non-streaming API responses
- i18n: remove redundant "Settings" suffix from setting tab translations (en/fr/ru/ja/vi)
- i18n: update "Group & Model Pricing" translations across all locales

controller/channel-test.go

@@ -150,6 +150,7 @@ func testChannel(channel *model.Channel, testModel string, endpointType string,
 		}
 	}
 	cache.WriteContext(c)
+	c.Set("id", 1)
 
 	//c.Request.Header.Set("Authorization", "Bearer "+channel.Key)
 	c.Request.Header.Set("Content-Type", "application/json")
@@ -274,7 +275,7 @@ func testChannel(channel *model.Channel, testModel string, endpointType string,
 		return testResult{
 			context:     c,
 			localErr:    err,
-			newAPIError: types.NewError(err, types.ErrorCodeModelPriceError),
+			newAPIError: types.NewError(err, types.ErrorCodeModelPriceError, types.ErrOptionWithStatusCode(http.StatusBadRequest)),
 		}
 	}
 
@@ -756,11 +757,15 @@ func TestChannel(c *gin.Context) {
 	tik := time.Now()
 	result := testChannel(channel, testModel, endpointType, isStream)
 	if result.localErr != nil {
-		c.JSON(http.StatusOK, gin.H{
+		resp := gin.H{
 			"success": false,
 			"message": result.localErr.Error(),
 			"time":    0.0,
-		})
+		}
+		if result.newAPIError != nil {
+			resp["error_code"] = result.newAPIError.GetErrorCode()
+		}
+		c.JSON(http.StatusOK, resp)
 		return
 	}
 	tok := time.Now()
@@ -769,9 +774,10 @@ func TestChannel(c *gin.Context) {
 	consumedTime := float64(milliseconds) / 1000.0
 	if result.newAPIError != nil {
 		c.JSON(http.StatusOK, gin.H{
-			"success": false,
-			"message": result.newAPIError.Error(),
-			"time":    consumedTime,
+			"success":    false,
+			"message":    result.newAPIError.Error(),
+			"time":       consumedTime,
+			"error_code": result.newAPIError.GetErrorCode(),
 		})
 		return
 	}

controller/relay.go

@@ -151,7 +151,7 @@ func Relay(c *gin.Context, relayFormat types.RelayFormat) {
 
 	priceData, err := helper.ModelPriceHelper(c, relayInfo, tokens, meta)
 	if err != nil {
-		newAPIError = types.NewError(err, types.ErrorCodeModelPriceError)
+		newAPIError = types.NewError(err, types.ErrorCodeModelPriceError, types.ErrOptionWithStatusCode(http.StatusBadRequest))
 		return
 	}