future-public: add set leverage request

examples/ChangeLeverageExample.php

@@ -0,0 +1,61 @@
+<?php
+
+/**
+ * Example usage of Change Leverage functionality
+ * 
+ * This example demonstrates how to use the LaravelBitunixApi package
+ * to change leverage for a trading pair on Bitunix exchange.
+ */
+
+require_once __DIR__ . '/../vendor/autoload.php';
+
+use Msr\LaravelBitunixApi\Requests\ChangeLeverageRequestContract;
+
+// Example configuration (in real usage, these would be in your .env file)
+config([
+    'bitunix-api.future_base_uri' => 'https://fapi.bitunix.com/',
+    'bitunix-api.api_key' => 'your-api-key-here',
+    'bitunix-api.api_secret' => 'your-api-secret-here',
+    'bitunix-api.language' => 'en-US',
+]);
+
+try {
+    // Get the API instance
+    $api = app(ChangeLeverageRequestContract::class);
+    
+    // Change leverage for BTCUSDT pair
+    $symbol = 'BTCUSDT';
+    $marginCoin = 'USDT';
+    $leverage = 12;
+    
+    echo "Changing leverage for {$symbol} to {$leverage}x...\n";
+    
+    $response = $api->changeLeverage($symbol, $marginCoin, $leverage);
+    
+    // Check response status
+    if ($response->getStatusCode() === 200) {
+        $data = json_decode($response->getBody()->getContents(), true);
+        
+        if ($data['code'] === 0) {
+            echo "✅ Leverage changed successfully!\n";
+            echo "Symbol: " . $data['data'][0]['symbol'] . "\n";
+            echo "Margin Coin: " . $data['data'][0]['marginCoin'] . "\n";
+            echo "New Leverage: " . $data['data'][0]['leverage'] . "\n";
+        } else {
+            echo "❌ API Error: " . $data['msg'] . "\n";
+        }
+    } else {
+        echo "❌ HTTP Error: " . $response->getStatusCode() . "\n";
+    }
+    
+} catch (Exception $e) {
+    echo "❌ Exception: " . $e->getMessage() . "\n";
+}
+
+/**
+ * Environment Variables Required:
+ * 
+ * BITUNIX_API_KEY=your-api-key
+ * BITUNIX_API_SECRET=your-api-secret
+ * BITUNIX_LANGUAGE=en-US
+ */