feat: contract uses num_lh, male avatar, captcha upgrade, full i18n

- Contract buy/close/cancel all use num_lh (contract balance) not num (spot)
- Wallet API returns contract (lh) account data block
- My.php returns user id field for frontend display
- Avatar: DiceBear avataaars male business style
- Captcha: 3x scaled text for readability
- Transfer log descriptions in English
- All billing descriptions in English

application/api/controller/Common.php

@@ -331,56 +331,56 @@ class Common extends Api
      */
     public function captcha()
     {
-        $a = mt_rand(1, 20);
-        $b = mt_rand(1, 20);
-        $operators = ['+', '-'];
-        $op = $operators[array_rand($operators)];
-        if ($op == '-' && $a < $b) {
-            // 确保减法结果非负
-            $tmp = $a; $a = $b; $b = $tmp;
+        // 生成4位随机大写英文字母
+        $chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ'; // 去掉易混淆的 I O
+        $answer = '';
+        for ($i = 0; $i < 4; $i++) {
+            $answer .= $chars[mt_rand(0, strlen($chars) - 1)];
         }
-        $answer = ($op == '+') ? ($a + $b) : ($a - $b);
-        $text = "{$a} {$op} {$b} = ?";
 
         // 生成唯一key标识本次验证码
         $captcha_key = md5(uniqid(mt_rand(), true));
+        cache('captcha_' . $captcha_key, strtoupper($answer), 300);
 
-        // 将答案存入缓存（使用ThinkPHP缓存，5分钟过期）
-        cache('captcha_' . $captcha_key, strval($answer), 300);
+        // 先在小画布绘制文字，再等比放大 → 让内置字体看起来更大
+        $smallW = 100;
+        $smallH = 32;
+        $small = imagecreatetruecolor($smallW, $smallH);
+        $smallBg = imagecolorallocate($small, 240, 244, 250);
+        imagefilledrectangle($small, 0, 0, $smallW, $smallH, $smallBg);
 
-        // 生成验证码图片
-        $width = 200;
-        $height = 60;
+        // 干扰线（小画布上）
+        for ($i = 0; $i < 3; $i++) {
+            $lc = imagecolorallocate($small, mt_rand(160, 210), mt_rand(160, 210), mt_rand(160, 210));
+            imageline($small, mt_rand(0, $smallW), mt_rand(0, $smallH), mt_rand(0, $smallW), mt_rand(0, $smallH), $lc);
+        }
+
+        // 文字（内置最大字号5，字符宽9px）
+        $fontSize = 5;
+        $charW = imagefontwidth($fontSize);
+        $charH = imagefontheight($fontSize);
+        $totalW = $charW * 4;
+        $startX = ($smallW - $totalW) / 2;
+        $startY = ($smallH - $charH) / 2;
+        for ($i = 0; $i < 4; $i++) {
+            $tc = imagecolorallocate($small, mt_rand(10, 70), mt_rand(10, 70), mt_rand(10, 70));
+            imagestring($small, $fontSize, (int)($startX + $i * $charW), (int)$startY, $answer[$i], $tc);
+        }
+
+        // 放大3倍到输出画布
+        $scale = 3;
+        $width  = $smallW * $scale;
+        $height = $smallH * $scale;
         $img = imagecreatetruecolor($width, $height);
+        imagecopyresampled($img, $small, 0, 0, 0, 0, $width, $height, $smallW, $smallH);
+        imagedestroy($small);
 
-        // 背景色
-        $bgColor = imagecolorallocate($img, 240, 244, 250);
-        imagefilledrectangle($img, 0, 0, $width, $height, $bgColor);
-
-        // 干扰线
-        for ($i = 0; $i < 5; $i++) {
-            $lineColor = imagecolorallocate($img, mt_rand(100, 200), mt_rand(100, 200), mt_rand(100, 200));
-            imageline($img, mt_rand(0, $width), mt_rand(0, $height), mt_rand(0, $width), mt_rand(0, $height), $lineColor);
+        // 干扰点（放大后再叠加，避免被放大模糊）
+        for ($i = 0; $i < 60; $i++) {
+            $dc = imagecolorallocate($img, mt_rand(150, 230), mt_rand(150, 230), mt_rand(150, 230));
+            imagesetpixel($img, mt_rand(0, $width), mt_rand(0, $height), $dc);
         }
 
-        // 干扰点
-        for ($i = 0; $i < 50; $i++) {
-            $dotColor = imagecolorallocate($img, mt_rand(100, 255), mt_rand(100, 255), mt_rand(100, 255));
-            imagesetpixel($img, mt_rand(0, $width), mt_rand(0, $height), $dotColor);
-        }
-
-        // 文字颜色
-        $textColor = imagecolorallocate($img, mt_rand(10, 80), mt_rand(10, 80), mt_rand(10, 80));
-
-        // 使用内置字体绘制文字
-        $fontSize = 5; // imagestring内置字体最大5
-        $textWidth = imagefontwidth($fontSize) * strlen($text);
-        $textHeight = imagefontheight($fontSize);
-        $x = ($width - $textWidth) / 2;
-        $y = ($height - $textHeight) / 2;
-        imagestring($img, $fontSize, $x, $y, $text, $textColor);
-
-        // 输出为base64
         ob_start();
         imagepng($img);
         $imgData = ob_get_clean();
@@ -406,7 +406,7 @@ class Common extends Api
         if ($answer === false || $answer === null) {
             return false;
         }
-        $result = (trim($captcha_code) === trim($answer));
+        $result = (strtoupper(trim($captcha_code)) === strtoupper(trim($answer)));
         // 验证后立即删除，防止重放
         cache('captcha_' . $captcha_key, null);
         return $result;