feat(dashboard): 添加特码热力图功能

在控制台增加特码热力图可视化功能：
- 新增 getSpecialHeatmap() 方法生成热力图数据
- 热力图展示近N期特码号码分布（X轴期号，Y轴号码1-49）
- 使用号码波色作为单元格颜色，直观展示开奖规律

application/admin/model/History.php

@@ -463,7 +463,70 @@ class History extends Model
             'oddeven' => $this->getOddEvenAnalysis($periods, 'special'),
             'bigsmall' => $this->getBigSmallAnalysis($periods, 'special'),
             'special' => $this->getSpecialTrend($periods),
-            'tailnumbers' => $this->getTailNumbers($periods, 'special')
+            'tailnumbers' => $this->getTailNumbers($periods, 'special'),
+            'heatmap' => $this->getSpecialHeatmap($periods)
+        ];
+    }
+
+    /**
+     * 特码热力图数据
+     * @param int $periods 查询最近多少期
+     * @return array {expects: [], heatmap: [[x, y, value]], colors: [号码对应颜色]}
+     */
+    public function getSpecialHeatmap($periods = 30)
+    {
+        $num_model = new Num();
+        $colorMap = $num_model->column('color', 'num');
+
+        // 查询最近 N 期特码数据
+        $history = $this
+            ->field('expect,num7,openTime')
+            ->order('openTime', 'desc')
+            ->limit($periods)
+            ->select();
+
+        if (empty($history)) {
+            return ['expects' => [], 'heatmap' => [], 'colors' => []];
+        }
+
+        // 反转数组，使数据从左到右为从远到近
+        $history = array_reverse($history);
+        $expects = [];
+        $heatmap = [];
+
+        // 构建热力图数据：[x_index, y_index, value]
+        // x_index = 期号索引（0到periods-1）
+        // y_index = 号码-1（0到48，号码1-49）
+        // value = 1（出现）或 0（未出现）
+        foreach ($history as $idx => $row) {
+            $expects[] = (string)$row['expect'];
+            $specialNum = (int)$row['num7'];
+            // 标记该期特码号码出现
+            if ($specialNum >= 1 && $specialNum <= 49) {
+                $heatmap[] = [$idx, $specialNum - 1, 1];
+            }
+        }
+
+        // 补充号码颜色映射（索引0对应号码1）
+        $colors = [];
+        for ($num = 1; $num <= 49; $num++) {
+            $color = $colorMap[$num] ?? '';
+            if (strpos($color, '红') !== false) {
+                $colors[] = '#e74c3c';
+            } elseif (strpos($color, '蓝') !== false) {
+                $colors[] = '#3498db';
+            } elseif (strpos($color, '绿') !== false) {
+                $colors[] = '#2ecc71';
+            } else {
+                $colors[] = '#95a5a6';
+            }
+        }
+
+        return [
+            'expects' => $expects,
+            'heatmap' => $heatmap,
+            'colors' => $colors,
+            'nums' => range(1, 49) // 号码列表
         ];
     }