Add drawing workspace feature

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

index.html

@@ -18,7 +18,8 @@
           <button id="nav-shape" class="step current" type="button" aria-current="step">① 형상 생성 <em id="step1-status">미생성</em></button>
           <button id="nav-plan" class="step" type="button">② 형상계획 <em id="step2-status">예정</em></button>
           <button id="nav-rebar" class="step" type="button">③ 철근배근 <em id="step3-status">예정</em></button>
-          <button id="nav-quantity" class="step" type="button">④ 재료표 <em id="step4-status">예정</em></button>
+          <button id="nav-drawing" class="step" type="button">④ 도면작성 <em id="step-drawing-status">형상 필요</em></button>
+          <button id="nav-quantity" class="step" type="button">⑤ 재료표 <em id="step4-status">예정</em></button>
         </nav>
         <div class="actions">
           <span id="save-status" class="savest">저장 전</span>
@@ -226,6 +227,8 @@
         </aside>
       </main>
 
+      <main id="view-drawing" hidden aria-label="교각 일반도 작성"></main>
+
       <main class="grid quantity" id="view-quantity" hidden>
         <aside class="panel piers" aria-labelledby="quantity-pier-title">
           <p id="quantity-pier-title" class="lbl">교각 목록</p>