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

web/public/icons/minimax.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none">
+  <rect width="24" height="24" rx="4" fill="#E45735"/>
+  <text x="12" y="16" text-anchor="middle" font-family="Arial, sans-serif" font-weight="bold" font-size="10" fill="white">M</text>
+</svg>

web/src/components/AITradersPage.tsx

@@ -96,6 +96,11 @@ const AI_PROVIDER_CONFIG: Record<string, {
     apiUrl: 'https://platform.moonshot.ai/console/api-keys',
     apiName: 'Moonshot',
   },
+  minimax: {
+    defaultModel: 'MiniMax-M2.5',
+    apiUrl: 'https://platform.minimax.io',
+    apiName: 'MiniMax',
+  },
 }
 
 interface AITradersPageProps {

web/src/components/ModelIcons.tsx

@@ -13,6 +13,7 @@ const MODEL_COLORS: Record<string, string> = {
   gemini: '#4285F4',
   grok: '#000000',
   openai: '#10A37F',
+  minimax: '#E45735',
 }
 
 // 获取AI模型图标的函数
@@ -44,6 +45,9 @@ export const getModelIcon = (modelType: string, props: IconProps = {}) => {
     case 'openai':
       iconPath = '/icons/openai.svg'
       break
+    case 'minimax':
+      iconPath = '/icons/minimax.svg'
+      break
     default:
       return null
   }

web/src/pages/DebateArenaPage.tsx

@@ -104,6 +104,7 @@ function AIAvatar({ name, size = 24 }: { name: string; size?: number }) {
     kimi: { bg: 'bg-purple-500', text: 'text-white', letter: 'K' },
     qwen: { bg: 'bg-indigo-500', text: 'text-white', letter: 'Q' },
     openai: { bg: 'bg-emerald-600', text: 'text-white', letter: 'O' },
+    minimax: { bg: 'bg-red-500', text: 'text-white', letter: 'M' },
     gpt: { bg: 'bg-emerald-600', text: 'text-white', letter: 'O' },
   }
   const lower = name.toLowerCase()