feat: [payroll] 입사월 급여 등록 시 일할계산 자동 적용

- 사원 선택 시 입사일이 해당 급여월이면 일할계산 자동 적용
- 산식: 월액 / 해당월총일수 × 근무일수 (입사일 포함)
- 기본급, 고정연장근로수당, 식대 모두 일할계산
- 일할계산 내역 안내 배너 표시 (산식, 금액 상세)
- 자동 적용 후 수동 수정 가능

resources/views/hr/payrolls/index.blade.php

@@ -187,6 +187,7 @@ class="w-full px-3 py-2 border border-gray-300 rounded-lg text-sm focus:ring-2 f
                                         data-base-salary="{{ $si['base_salary'] ?? 0 }}"
                                         data-overtime-pay="{{ $si['fixed_overtime_pay'] ?? 0 }}"
                                         data-meal-allowance="{{ $si['meal_allowance'] ?? 200000 }}"
+                                        data-hire-date="{{ $emp->getJsonExtraValue('hire_date', '') }}"
                                         data-dependents="{{ 1 + collect($emp->dependents)->where('is_dependent', true)->count() }}">
                                     {{ $emp->display_name ?? $emp->user?->name }}
                                 </option>
@@ -206,6 +207,36 @@ class="w-full px-3 py-2 border border-gray-300 rounded-lg text-sm focus:ring-2 f
                     </div>
                 </div>
 
+                {{-- 일할계산 안내 (입사월인 경우) --}}
+                <div id="prorataNotice" class="hidden rounded-lg border border-amber-300 bg-amber-50 p-3">
+                    <div class="flex items-start gap-2">
+                        <svg class="w-4 h-4 text-amber-600 mt-0.5 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M12 9v3.75m9-.75a9 9 0 11-18 0 9 9 0 0118 0zm-9 3.75h.008v.008H12v-.008z"/>
+                        </svg>
+                        <div class="text-xs text-amber-800">
+                            <p class="font-semibold mb-1">일할계산 적용</p>
+                            <p id="prorataDesc"></p>
+                            <table class="mt-2 w-full text-xs border border-amber-200">
+                                <thead>
+                                    <tr class="bg-amber-100">
+                                        <th class="border border-amber-200 px-2 py-1 text-left">항목</th>
+                                        <th class="border border-amber-200 px-2 py-1 text-right">월액</th>
+                                        <th class="border border-amber-200 px-2 py-1 text-center">산식</th>
+                                        <th class="border border-amber-200 px-2 py-1 text-right">일할금액</th>
+                                    </tr>
+                                </thead>
+                                <tbody id="prorataTableBody"></tbody>
+                                <tfoot>
+                                    <tr class="bg-amber-100 font-semibold">
+                                        <td class="border border-amber-200 px-2 py-1" colspan="3">합계</td>
+                                        <td class="border border-amber-200 px-2 py-1 text-right" id="prorataTotal"></td>
+                                    </tr>
+                                </tfoot>
+                            </table>
+                        </div>
+                    </div>
+                </div>
+
                 {{-- 지급 항목 --}}
                 <div>
                     <h4 class="text-sm font-medium text-gray-700 mb-2">지급 항목</h4>
@@ -997,6 +1028,7 @@ function openCreatePayrollModal() {
         document.getElementById('payrollPayMonth').value = document.getElementById('payrollMonth').value;
         document.getElementById('allowancesContainer').innerHTML = '';
         document.getElementById('deductionsContainer').innerHTML = '';
+        hideProrataNotice();
         resetCalculation();
         document.getElementById('payrollModal').classList.remove('hidden');
     }
@@ -1055,6 +1087,58 @@ function closePayrollModal() {
         document.getElementById('payrollUserId').disabled = false;
     }
 
+    // ===== 일할계산 유틸 =====
+    function getDaysInMonth(year, month) {
+        return new Date(year, month, 0).getDate();
+    }
+
+    function checkProrata(hireDate, payYear, payMonth) {
+        if (!hireDate) return null;
+        const d = new Date(hireDate);
+        if (d.getFullYear() === payYear && (d.getMonth() + 1) === payMonth) {
+            const totalDays = getDaysInMonth(payYear, payMonth);
+            const workDays = totalDays - d.getDate() + 1;
+            return { hireDate, totalDays, workDays, hireDay: d.getDate() };
+        }
+        return null;
+    }
+
+    function applyProrata(amount, totalDays, workDays) {
+        return Math.round(amount / totalDays * workDays);
+    }
+
+    function showProrataNotice(prorata, baseSalary, overtimePay, mealAllowance) {
+        const notice = document.getElementById('prorataNotice');
+        const desc = document.getElementById('prorataDesc');
+        const tbody = document.getElementById('prorataTableBody');
+        const total = document.getElementById('prorataTotal');
+
+        desc.textContent = `입사일: ${prorata.hireDate} | 근무일수: ${prorata.workDays}일 / ${prorata.totalDays}일`;
+
+        const items = [
+            { name: '기본급', amount: baseSalary },
+            { name: '식대', amount: mealAllowance },
+            { name: '고정연장근로수당', amount: overtimePay },
+        ];
+        let sum = 0;
+        tbody.innerHTML = items.map(item => {
+            const pro = applyProrata(item.amount, prorata.totalDays, prorata.workDays);
+            sum += pro;
+            return `<tr>
+                <td class="border border-amber-200 px-2 py-1">${item.name}</td>
+                <td class="border border-amber-200 px-2 py-1 text-right">${numberFormat(item.amount)}</td>
+                <td class="border border-amber-200 px-2 py-1 text-center">${numberFormat(item.amount)}/${prorata.totalDays}*${prorata.workDays}</td>
+                <td class="border border-amber-200 px-2 py-1 text-right font-medium">${numberFormat(pro)}</td>
+            </tr>`;
+        }).join('');
+        total.textContent = numberFormat(sum);
+        notice.classList.remove('hidden');
+    }
+
+    function hideProrataNotice() {
+        document.getElementById('prorataNotice').classList.add('hidden');
+    }
+
     // ===== 사원 선택 시 급여 산정값 자동 입력 + 가족수 표시 =====
     document.getElementById('payrollUserId').addEventListener('change', function() {
         const selected = this.options[this.selectedIndex];
@@ -1062,17 +1146,34 @@ function closePayrollModal() {
         const fcEl = document.getElementById('calcFamilyCount');
         if (fcEl) fcEl.textContent = dependents + '명';
 
+        hideProrataNotice();
         if (editingPayrollId) return;
 
         const baseSalary = parseInt(selected.dataset.baseSalary || 0);
         const overtimePay = parseInt(selected.dataset.overtimePay || 0);
         const mealAllowance = parseInt(selected.dataset.mealAllowance || 0);
+        const hireDate = selected.dataset.hireDate || '';
+
+        let finalBase = baseSalary;
+        let finalOT = overtimePay;
+        let finalMeal = mealAllowance;
 
         if (baseSalary > 0) {
-            // 연봉 산정 테이블에서 계산된 값 적용
-            setMoneyValue(document.getElementById('payrollBaseSalary'), baseSalary);
-            setMoneyValue(document.getElementById('payrollOvertimePay'), overtimePay);
-            setMoneyValue(document.getElementById('payrollBonus'), mealAllowance);
+            // 일할계산 체크
+            const payYear = parseInt(document.getElementById('payrollPayYear').value);
+            const payMonth = parseInt(document.getElementById('payrollPayMonth').value);
+            const prorata = checkProrata(hireDate, payYear, payMonth);
+
+            if (prorata && prorata.workDays < prorata.totalDays) {
+                finalBase = applyProrata(baseSalary, prorata.totalDays, prorata.workDays);
+                finalOT = applyProrata(overtimePay, prorata.totalDays, prorata.workDays);
+                finalMeal = applyProrata(mealAllowance, prorata.totalDays, prorata.workDays);
+                showProrataNotice(prorata, baseSalary, overtimePay, mealAllowance);
+            }
+
+            setMoneyValue(document.getElementById('payrollBaseSalary'), finalBase);
+            setMoneyValue(document.getElementById('payrollOvertimePay'), finalOT);
+            setMoneyValue(document.getElementById('payrollBonus'), finalMeal);
         } else {
             // fallback: 산정 데이터 없으면 연봉에서 단순 계산
             const salary = parseInt(selected.dataset.salary || 0);