feat: add MiniMax provider support (#1406)

Add MiniMax as a new AI model provider with OpenAI-compatible API.

Supported models:
- MiniMax-M2.5 (default) - Peak Performance, Ultimate Value
- MiniMax-M2.5-highspeed - Same performance, faster and more agile

Changes:
- Add MiniMax client (mcp/minimax_client.go) with OpenAI-compatible API
- Add comprehensive unit tests (mcp/minimax_client_test.go)
- Add WithMiniMaxConfig option (mcp/options.go)
- Register MiniMax provider in trader, debate engine, backtest, and API
- Add MiniMax to frontend provider config and model icons
- Add MiniMax SVG icon

API Base URL: https://api.minimax.io/v1

api/backtest.go

@@ -832,6 +832,8 @@ func (s *Server) hydrateBacktestAIConfig(cfg *backtest.BacktestConfig) error {
 			provider = "google"
 		} else if strings.Contains(modelNameLower, "deepseek") {
 			provider = "deepseek"
+		} else if strings.Contains(modelNameLower, "minimax") {
+			provider = "minimax"
 		} else if model.CustomAPIURL != "" {
 			provider = "custom"
 		} else {

api/server.go

@@ -1683,6 +1683,7 @@ func (s *Server) handleGetModelConfigs(c *gin.Context) {
 			{ID: "gemini", Name: "Gemini AI", Provider: "gemini", Enabled: false},
 			{ID: "grok", Name: "Grok AI", Provider: "grok", Enabled: false},
 			{ID: "kimi", Name: "Kimi AI", Provider: "kimi", Enabled: false},
+			{ID: "minimax", Name: "MiniMax AI", Provider: "minimax", Enabled: false},
 		}
 		c.JSON(http.StatusOK, defaultModels)
 		return
@@ -3252,6 +3253,7 @@ func (s *Server) handleGetSupportedModels(c *gin.Context) {
 		{"id": "gemini", "name": "Google Gemini", "provider": "gemini", "defaultModel": "gemini-3-pro-preview"},
 		{"id": "grok", "name": "Grok (xAI)", "provider": "grok", "defaultModel": "grok-3-latest"},
 		{"id": "kimi", "name": "Kimi (Moonshot)", "provider": "kimi", "defaultModel": "moonshot-v1-auto"},
+		{"id": "minimax", "name": "MiniMax", "provider": "minimax", "defaultModel": "MiniMax-M2.5"},
 	}
 
 	c.JSON(http.StatusOK, supportedModels)

api/strategy.go

@@ -625,6 +625,9 @@ func (s *Server) runRealAITest(userID, modelID, systemPrompt, userPrompt string)
 	case "openai":
 		aiClient = mcp.NewOpenAIClient()
 		aiClient.SetAPIKey(apiKey, model.CustomAPIURL, model.CustomModelName)
+	case "minimax":
+		aiClient = mcp.NewMiniMaxClient()
+		aiClient.SetAPIKey(apiKey, model.CustomAPIURL, model.CustomModelName)
 	default:
 		// Use generic client
 		aiClient = mcp.NewClient()