add more controllers and fix tests

app/Services/Fees/FeeGradeService.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Services\Fees;
+
+class FeeGradeService
+{
+    public function normalizeGrade(?string $grade): string
+    {
+        return strtoupper(trim((string) $grade));
+    }
+
+    public function compareGrades(string $gradeA, string $gradeB): int
+    {
+        $valA = $this->getGradeLevel($gradeA);
+        $valB = $this->getGradeLevel($gradeB);
+
+        if ($valA !== $valB) {
+            return $valA <=> $valB;
+        }
+
+        preg_match('/\d+([A-Z]*)$/i', strtoupper($gradeA), $suffixA);
+        preg_match('/\d+([A-Z]*)$/i', strtoupper($gradeB), $suffixB);
+
+        return strcmp($suffixA[1] ?? '', $suffixB[1] ?? '');
+    }
+
+    public function getGradeLevel(string $grade): int
+    {
+        $grade = $this->normalizeGrade($grade);
+
+        if ($grade === 'K') {
+            return 0;
+        }
+        if ($grade === 'Y') {
+            return 99;
+        }
+
+        if (preg_match('/^(\d+)([A-Z]*)$/i', $grade, $matches)) {
+            return (int) $matches[1];
+        }
+
+        return 999;
+    }
+}