feat: ABV 레벨 및 퍼센트 라벨링 기능 추가

Author: MEOHIN

src/main/java/com/back/domain/user/support/AbvView.java

@@ -0,0 +1,28 @@
+package com.back.domain.user.support;
+
+public final class AbvView {
+
+    private AbvView(){}
+
+    // 0~100%를 6단계로 매핑
+    public static int levelOf(Double percent) {
+        if (percent == null) return 1;
+
+        double x = Math.max(0, Math.min(100, percent));
+        int p = (int) x;
+
+        if (p <= 10) return 1;      // 0~10
+        if (p <= 25) return 2;      // 11~25
+        if (p <= 45) return 3;      // 26~45
+        if (p <= 65) return 4;      // 46~65
+        if (p <= 85) return 5;      // 66~85
+        return 6;                   // 86~100
+    }
+
+    // 화면용 "23.5%" 라벨
+    public static String percentLabel(Double percent) {
+        if (percent == null) return "0%";
+        double x = Math.max(0.0, Math.min(100.0, percent));
+        return (x % 1.0 == 0.0) ? String.format("%.0f%%", x) : String.format("%.1f%%", x);
+    }
+}