fix(detailedReport): BMI 刻度落点按四段分界计算并计入色块间隙

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

miniprogram/pages/detailedReport/detailedReport.ts

@@ -159,11 +159,28 @@ const splitWeight = (weight: number): { int: string; decimal: string } => {
     return { int, decimal: `.${dec}` }
 }
 
-/** 根据 BMI 计算刻度圆圈位置（百分比） */
+/**
+ * 刻度轨道结构（rpx）：屏宽 750 - basicIndicators 左右 padding 30*2 - 左右 border 4*2 = 682。
+ * BLOCK_GAP 与 less 中 basicIndicatorsTrack 的 gap: 6rpx 保持同步。
+ */
+const TRACK_WIDTH = 682
+const BLOCK_GAP = 6
+const BLOCK_WIDTH = (TRACK_WIDTH - BLOCK_GAP * 3) / 4
+
+/** 根据 BMI 计算刻度圆圈圆心位置（百分比），对齐消瘦/正常/超重/肥胖四段分界 18.5/24/28，并计入色块间隙 */
 const calcBmiLeft = (bmi?: number): number => {
     if (bmi == null || isNaN(bmi)) return 0
-    const pct = (bmi - 14) / (40 - 14)
-    return Math.min(Math.max(pct, 0), 1) * 100
+    let left: number
+    if (bmi < 18.5) {
+        left = (bmi / 18.5) * BLOCK_WIDTH
+    } else if (bmi < 24) {
+        left = BLOCK_WIDTH + BLOCK_GAP + ((bmi - 18.5) / (24 - 18.5)) * BLOCK_WIDTH
+    } else if (bmi < 28) {
+        left = BLOCK_WIDTH * 2 + BLOCK_GAP * 2 + ((bmi - 24) / (28 - 24)) * BLOCK_WIDTH
+    } else {
+        left = BLOCK_WIDTH * 3 + BLOCK_GAP * 3 + ((bmi - 28) / (40 - 28)) * BLOCK_WIDTH
+    }
+    return Math.min(Math.max(left / TRACK_WIDTH, 0), 1) * 100
 }
 
 Page({