fix: remove legend from plot, keep only canvas in square frame

app/src/main/assets/console.js

@@ -530,30 +530,6 @@ class SymjaConsole {
         canvas.style.height = '500px';
         container.appendChild(canvas);
 
-        // 图例（多曲线时自动显示）
-        let legendVisible = true;
-        let legendEl = null;
-        if (data.elements && data.elements.length > 1) {
-            legendEl = this.buildLegend(data, labels);
-            if (legendEl) container.appendChild(legendEl);
-        }
-
-        // 图例开关（仅在多曲线时显示）
-        if (legendEl) {
-            const actions = document.createElement('div');
-            actions.className = 'plot-actions';
-            const legendBtn = document.createElement('button');
-            legendBtn.className = 'plot-save-btn';
-            legendBtn.textContent = '🏷 图例';
-            legendBtn.onclick = () => {
-                legendVisible = !legendVisible;
-                legendEl.style.display = legendVisible ? 'flex' : 'none';
-                legendBtn.style.opacity = legendVisible ? '1' : '0.5';
-            };
-            actions.appendChild(legendBtn);
-            container.appendChild(actions);
-        }
-
         // 长按保存（单指静止800ms触发）
         let longPressTimer;
         canvas.addEventListener('touchstart', (e) => {