fix: 可视化编辑模式去除 doc-edit-page 大内边距

- DocRenderer 移出 .doc-edit-page 容器，使用独立的 .doc-visual-wrap
- 避免 iframe 内部 padding 与外部 padding 叠加导致可视区域过小

web/src/views/TemplateEditor.vue

@@ -97,7 +97,19 @@
         </div>
 
         <div class="center-scroll">
-          <div class="doc-edit-page">
+          <div v-if="editorMode === 'visual'" class="doc-visual-wrap">
+            <DocRenderer
+              ref="docRendererRef"
+              :key="previewKey"
+              :html-content="previewHtml"
+              :blocks="previewBlocks"
+              initial-mode="select"
+              @block-select="onBlockSelect"
+              @block-set-ai="onBlockSetAI"
+              @block-set-fixed="onBlockSetFixed"
+            />
+          </div>
+          <div v-else class="doc-edit-page">
             <template v-if="editorMode === 'paragraph'">
               <div v-for="paragraph in paragraphs" :key="paragraph.id" :id="`paraBlock${paragraph.id}`" :class="['para-block', { selected: selectedId === paragraph.id }]" @click="selectPara(paragraph.id)">
                 <span class="para-block-actions" @click.stop>
@@ -119,18 +131,6 @@
                 <p v-else class="empty-text">点击左侧配置此段落。</p>
               </div>
             </template>
-            <template v-else-if="editorMode === 'visual'">
-              <DocRenderer
-                ref="docRendererRef"
-                :key="previewKey"
-                :html-content="previewHtml"
-                :blocks="previewBlocks"
-                initial-mode="select"
-                @block-select="onBlockSelect"
-                @block-set-ai="onBlockSetAI"
-                @block-set-fixed="onBlockSetFixed"
-              />
-            </template>
             <template v-else>
               <div
                 v-for="paragraph in paragraphs"
@@ -1088,6 +1088,13 @@ onMounted(async () => {
   flex-shrink: 0;
 }
 
+.doc-visual-wrap {
+  width: 100%;
+  flex: 1;
+  display: flex;
+  flex-direction: column;
+}
+
 .para-block {
   position: relative;
   padding: 8px;