fix(proxy-input): worker_id→user_id 수정 + 공통 입력 UI로 변경

백엔드:
- proxyInputModel 전체 worker_id→user_id 전환
  (작업보고서/휴가 매핑 실패 → 전부 미입력으로 표시되던 문제)

프론트:
- 개별 입력 → 공통 입력 1개로 전환
  프로젝트/공종/시간/부적합 한번 입력 → 선택된 전원에 적용
- 부서별 그룹핑 표시
- 적용 대상 칩 표시

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

system1-factory/web/pages/work/proxy-input.html

@@ -73,7 +73,22 @@
             <h2 class="pi-title" id="editTitle">일괄 편집</h2>
         </div>
 
-        <div class="pi-edit-list" id="editList"></div>
+        <div class="pi-bulk-form">
+            <div class="pi-edit-row">
+                <select id="bulkProject" class="pi-select" required></select>
+                <select id="bulkWorkType" class="pi-select" required></select>
+            </div>
+            <div class="pi-edit-row">
+                <label class="pi-field"><span>시간</span><input type="number" id="bulkHours" value="8" step="0.5" min="0" max="24" class="pi-input"></label>
+                <label class="pi-field"><span>부적합</span><input type="number" id="bulkDefect" value="0" step="0.5" min="0" max="24" class="pi-input"></label>
+            </div>
+            <input type="text" id="bulkNote" placeholder="비고 (선택)" class="pi-note-input">
+        </div>
+
+        <div class="pi-target-section">
+            <div class="pi-target-label">적용 대상</div>
+            <div class="pi-target-list" id="targetWorkers"></div>
+        </div>
 
         <div class="pi-bottom-bar">
             <button class="pi-save-btn" id="saveBtn" onclick="saveAll()">