Add adaptive coordinate guides to canvas editor

核桃派软件源代码/app/static/index.html

@@ -104,6 +104,7 @@
               <canvas id="scene-overlay" width="64" height="64" aria-label="统一画板交互层"></canvas>
               <div id="pixel-grid" class="pixel-grid" aria-hidden="true" hidden></div>
             </div>
+            <canvas id="canvas-coordinate-guide" class="canvas-coordinate-guide" aria-hidden="true" hidden></canvas>
             <p id="board-status" class="board-status" aria-live="polite">正在恢复画板草稿…</p>
             <div class="board-actions">
               <button id="apply-composition" class="primary-button" type="button">应用统一画板</button>
@@ -118,6 +119,7 @@
               </button>
               <div id="canvas-assistive-menu" class="canvas-assistive-menu" role="menu" aria-label="画布编辑操作" hidden>
                 <p id="canvas-edit-mode-hint" role="status" aria-live="polite">绘画模式：直接在画布上绘制</p>
+                <button id="toggle-canvas-coordinates" type="button" role="menuitem" aria-pressed="false">显示坐标系</button>
                 <button id="undo-canvas-edit" type="button" role="menuitem" aria-disabled="true"
                   data-unavailable-reason="还没有可以撤销的像素操作。">撤销</button>
                 <button id="exit-canvas-edit" type="button" role="menuitem">退出编辑</button>