feat: 添加NIMConfigurationManager和AppConfig文件

添加NIMConfigurationManager用于初始化NIM SDK，并创建AppConfig以管理应用环境配置，包括基础URL和Analytics Key等

yana/Configs/AppConfig.swift

@@ -0,0 +1,36 @@
+enum Environment {
+    case development
+    case production
+}
+
+struct AppConfig {
+    static var current: Environment = {
+        #if DEBUG
+        return .development
+        #else
+        return .production
+        #endif
+    }()
+    
+    static var baseURL: String {
+        switch current {
+        case .development:
+            return "https://dev-api.yourdomain.com/v1"
+        case .production:
+            return "https://api.yourdomain.com/v1"
+        }
+    }
+    
+    // 添加更多环境变量
+    static var analyticsKey: String {
+        switch current {
+        case .development: return "dev_analytics_key"
+        case .production: return "prod_analytics_key"
+        }
+    }
+    
+    // 运行时切换环境（用于测试）
+    static func switchEnvironment(to env: Environment) {
+        current = env
+    }
+}