feat: 完善模型用量趋势与全局手账卡片并补齐阶段验收

frontend/src/utils/diagramControls.ts

@@ -0,0 +1,14 @@
+/** Markup survives Milkdown's preview copying; the enclosing Vue component handles clicks. */
+export function appendDiagramControls(container: HTMLElement) {
+  const controls = document.createElement('div')
+  controls.className = 'diagram-controls'
+  controls.setAttribute('contenteditable', 'false')
+  for (const [action, label] of [['out', '缩小图表'], ['in', '放大图表'], ['reset', '重置缩放'], ['view', '大图查看']]) {
+    const button = document.createElement('button')
+    button.type = 'button'
+    button.dataset.diagramAction = action
+    button.textContent = label
+    controls.append(button)
+  }
+  container.append(controls)
+}