refactor(typesetting): Wave2 - 表格字号移位+画布header+对齐下拉+移除历史UI

- T3: 表格字号从设置弹框移到渲染预览header工具栏
- T4: 画布预览区添加header bar和重置对齐按钮
- T5: 对齐按钮改为select下拉，change仅CSS操作不重渲染
- T6: 移除历史记录UI(按钮/菜单/处理函数/URL变量)
- CSS: alignment-toggle样式替换为alignment-select样式

public/static/css/phone-image-templates.css

@@ -569,42 +569,26 @@
     margin-top: 6px;
 }
 
-.thumb-alignment-toggle {
+.thumb-alignment-select {
     position: absolute;
-    top: 8px;
-    right: 8px;
+    bottom: 4px;
+    right: 4px;
+    height: 22px;
+    font-size: 11px;
+    border: 1px solid #d9d9d9;
+    border-radius: 3px;
+    padding: 0 2px;
+    background: #fff;
+    cursor: pointer;
     z-index: 10;
     opacity: 0;
-    width: 24px;
-    height: 24px;
-    border-radius: 4px;
-    background: rgba(0, 0, 0, 0.06);
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    font-size: calc(14px * var(--pi-font-scale, 1));
-    color: #666;
-    user-select: none;
-    border: none;
-    padding: 0;
-    cursor: pointer;
     transition: opacity 0.2s;
 }
 
-.preview-thumb-item:hover .thumb-alignment-toggle {
+.preview-thumb-item:hover .thumb-alignment-select {
     opacity: 1;
 }
 
-.thumb-alignment-toggle:hover {
-    background: rgba(0, 0, 0, 0.1);
-}
-
-.thumb-alignment-toggle.active-center {
-    opacity: 1;
-    background: rgba(24, 144, 255, 0.15);
-    color: #1890ff;
-}
-
 /* ============================================
    Content Flow Code Blocks (中间栏代码块样式)
    仅用于编辑区中间栏, 不影响渲染页面