feat(phone-image): 段落按行截断+overflow跨頁續接

- paginateContent新增overflow截斷：剩餘空間>40px時放入當前頁(CSS裁切)
- generateContentPage新增overflowOffset參數：續接頁用負margin-top偏移
- 跨多頁溢出while循環處理：單個塊可跨越3+頁
- 保留orphan control和splitOversizedBlock邏輯
- 不限制塊類型：段落/表格/代碼塊/圖片都可截斷

public/static/js/phone-image.js

@@ -619,6 +619,7 @@ var PhoneImageEngine = (function () {
         var currentPageBlocks = [];
         var currentHeight = 0;
         var pageNumber = 1;
+        var currentPageOverflowOffset = 0; // 续接页偏移量，0表示普通页
 
         for (var i = 0; i < blocks.length; i++) {
             var block = blocks[i];
@@ -628,10 +629,11 @@ var PhoneImageEngine = (function () {
                 // 结束当前页
                 if (currentPageBlocks.length > 0) {
                     contentPages.push(generateContentPage(
-                        currentPageBlocks, pageNumber, sizeConfig, false
+                        currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
                     ));
                     currentPageBlocks = [];
                     currentHeight = 0;
+                    currentPageOverflowOffset = 0;
                     pageNumber++;
                 }
                 continue;  // 跳过这个 page-break 块本身
@@ -651,10 +653,11 @@ var PhoneImageEngine = (function () {
                 // 先把当前页已有的内容推出去
                 if (currentPageBlocks.length > 0) {
                     contentPages.push(generateContentPage(
-                        currentPageBlocks, pageNumber, sizeConfig, false
+                        currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
                     ));
                     currentPageBlocks = [];
                     currentHeight = 0;
+                    currentPageOverflowOffset = 0;
                     pageNumber++;
                 }
 
@@ -670,10 +673,11 @@ var PhoneImageEngine = (function () {
                     var sb = splitBlocks[s];
                     if (currentHeight + sb.estimatedHeight > contentAreaHeight && currentPageBlocks.length > 0) {
                         contentPages.push(generateContentPage(
-                            currentPageBlocks, pageNumber, sizeConfig, false
+                            currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
                         ));
                         currentPageBlocks = [];
                         currentHeight = 0;
+                        currentPageOverflowOffset = 0;
                         pageNumber++;
                     }
                     currentPageBlocks.push(sb);
@@ -688,37 +692,46 @@ var PhoneImageEngine = (function () {
 
             if (currentHeight + block.estimatedHeight > contentAreaHeight && currentPageBlocks.length > 0) {
                 var remainingSpace = contentAreaHeight - currentHeight;
-                // 检查是否可以按句拆分来填满剩余空间
-                var canSplit = (block.type === 'p' || block.type === 'blockquote') &&
-                    block.estimatedHeight <= contentAreaHeight && remainingSpace > 50;
+                if (remainingSpace > 40) {
+                    // 放入当前页，CSS overflow:hidden 截断溢出部分
+                    currentPageBlocks.push(block);
 
-                if (canSplit) {
-                    // 按句拆分，逐步填入页面
-                    var splitParts = splitOversizedBlock(block, contentAreaHeight);
-                    if (splitParts.length > 1) {
-                        // 逐句填入当前页剩余空间
-                        for (var sp = 0; sp < splitParts.length; sp++) {
-                            if (currentHeight + splitParts[sp].estimatedHeight > contentAreaHeight && currentPageBlocks.length > 0) {
-                                contentPages.push(generateContentPage(
-                                    currentPageBlocks, pageNumber, sizeConfig, false
-                                ));
-                                currentPageBlocks = [];
-                                currentHeight = 0;
-                                pageNumber++;
-                            }
-                            currentPageBlocks.push(splitParts[sp]);
-                            currentHeight += splitParts[sp].estimatedHeight;
-                        }
-                        // 跳过后面的 currentPageBlocks.push(block)，用拆分后的块代替
-                        continue;
+                    // 推出当前页（含溢出块，视觉上被 .page-content { overflow:hidden } 裁切）
+                    contentPages.push(generateContentPage(
+                        currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
+                    ));
+                    pageNumber++;
+
+                    // 续接：下一页从截断处继续显示同一个块
+                    var overflowOffset = remainingSpace;
+                    var remainingHeight = block.estimatedHeight - overflowOffset;
+
+                    // 处理跨多页溢出（一个块可能跨越3+页）
+                    while (remainingHeight > contentAreaHeight) {
+                        contentPages.push(generateContentPage(
+                            [block], pageNumber, sizeConfig, false, overflowOffset
+                        ));
+                        pageNumber++;
+                        overflowOffset += contentAreaHeight;
+                        remainingHeight -= contentAreaHeight;
                     }
+
+                    // 最后一部分续接，后续块可以继续添加到这一页
+                    currentPageBlocks = [block];
+                    currentHeight = remainingHeight;
+                    currentPageOverflowOffset = overflowOffset;
+
+                    // 块已在上方处理完毕，跳过底部的默认 push
+                    continue;
                 }
-                // 不可拆分(img/pre/table/h)或拆分失败，直接换页
+
+                // 剩余空间太小(<40px)，不值得截断，直接换页
                 contentPages.push(generateContentPage(
-                    currentPageBlocks, pageNumber, sizeConfig, false
+                    currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
                 ));
                 currentPageBlocks = [];
                 currentHeight = 0;
+                currentPageOverflowOffset = 0;
                 pageNumber++;
             }
 
@@ -732,12 +745,13 @@ var PhoneImageEngine = (function () {
                     currentHeight -= block.estimatedHeight;
                     if (currentPageBlocks.length > 0) {
                         contentPages.push(generateContentPage(
-                            currentPageBlocks, pageNumber, sizeConfig, false
+                            currentPageBlocks, pageNumber, sizeConfig, false, currentPageOverflowOffset
                         ));
                         pageNumber++;
                     }
                     currentPageBlocks = [block];
                     currentHeight = block.estimatedHeight;
+                    currentPageOverflowOffset = 0;
                 }
             }
         }
@@ -745,7 +759,7 @@ var PhoneImageEngine = (function () {
         // 最后一页
         if (currentPageBlocks.length > 0) {
             contentPages.push(generateContentPage(
-                currentPageBlocks, pageNumber, sizeConfig, true
+                currentPageBlocks, pageNumber, sizeConfig, true, currentPageOverflowOffset
             ));
         }
 
@@ -1039,7 +1053,7 @@ var PhoneImageEngine = (function () {
     /**
      * 生成内容页HTML（含逐页对齐支持）
      */
-    function generateContentPage(blocks, pageNum, sizeConfig, isLast) {
+    function generateContentPage(blocks, pageNum, sizeConfig, isLast, overflowOffset) {
         // 读取逐页对齐配置
         var alignment = (config.pageAlignments && config.pageAlignments[pageNum]) || 'top';
         var valignClass = '';
@@ -1067,9 +1081,16 @@ var PhoneImageEngine = (function () {
 
         // 正文内容区
         html += '<div class="page-content">';
+        // 续接页：用内层div+负margin-top偏移，使截断处之后的内容可见
+        if (overflowOffset && overflowOffset > 0) {
+            html += '<div style="margin-top:-' + overflowOffset + 'px;">';
+        }
         for (var i = 0; i < blocks.length; i++) {
             html += blocks[i].html;
         }
+        if (overflowOffset && overflowOffset > 0) {
+            html += '</div>';
+        }
         html += '</div>';
 
         // 页脚 - 占位，render() 中会替换页码