feat: 添加图片编辑器，与文本共用工具栏，选中切换编辑面板，支持图片透明度调节

css/style.css

@@ -79,12 +79,15 @@ html, body {
     display: block;
 }
 
-/* 文本编辑器工具栏 */
-.text-editor-toolbar {
+/* 编辑器工具栏（文本/图片共用） */
+.editor-toolbar {
+    position: absolute;
+    top: 49px;
+    left: 0;
+    right: 0;
     display: flex;
     justify-content: center;
     align-items: center;
-    gap: 8px;
     padding: 10px 16px;
     background: #fff;
     border-bottom: 1px solid #e0e0e0;
@@ -92,13 +95,25 @@ html, body {
     visibility: hidden;
     opacity: 0;
     transition: opacity 0.2s;
+    z-index: 100;
 }
 
-.text-editor-toolbar.active {
+.editor-toolbar.active {
     visibility: visible;
     opacity: 1;
 }
 
+.toolbar-group {
+    display: none;
+    justify-content: center;
+    align-items: center;
+    gap: 8px;
+}
+
+.toolbar-group.active {
+    display: flex;
+}
+
 .toolbar-btn {
     width: 40px;
     height: 40px;
@@ -150,6 +165,14 @@ html, body {
     cursor: pointer;
 }
 
+.opacity-slider {
+    width: 120px;
+    height: 40px;
+    cursor: pointer;
+    accent-color: #4a90e2;
+    margin: 0;
+}
+
 /* 字号滚轮选择器 */
 .roller-picker {
     display: flex;