fix(data-process): 优化预览分页与PDF兼容

frontend/src/views/data-process/create/PdfSourceViewer.vue

@@ -220,10 +220,12 @@ async function renderCurrentPage(force = false) {
       ) return
       throw error
     })
-    const textContent = await page.getTextContent()
+    // WebKit 兼容：PDF.js 的 getTextContent() 依赖 ReadableStream 异步迭代，
+    // 部分 Safari/WKWebView 未实现该接口。TextLayer 可直接通过 getReader() 消费文本流。
+    const textContentSource = page.streamTextContent()
     if (sequence !== renderSequence) return
     const activeTextLayer = new TextLayer({
-      textContentSource: textContent,
+      textContentSource,
       container: layerContainer,
       viewport,
     })