feat(pdf): support GraphRAG text_bbox highlighting in PDF viewer

When documents are processed through GraphRAG pipeline, coordinate
enrichment produces text_bbox (paragraph-level coordinates) instead of
char_positions (character-level OCR coordinates). Added resolveCharPositions()
helper that converts text_bbox to CharPosition[] format, enabling PDF
highlight rendering for GraphRAG-processed documents.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/components/reviews/previewComponents/PdfPreview.tsx

@@ -38,6 +38,7 @@ interface PdfPreviewProps {
   filePath: string; // PDF 文件路径
   targetPage?: number; // 目标页码
   charPositions?: Array<{ box: number[][], char: string, score: number }>; // 字符位置信息（用于高亮显示）
+  textBbox?: { x_min: number; y_min: number; x_max: number; y_max: number }; // GraphRAG段落级坐标
   isStructuredView?: boolean; // 是否结构化视图
   activeReviewPointResultId?: string | null; // 激活的评查点结果ID
   pageOffset?: number; // 页码偏移量（用于调整 OCR 结果的页码）
@@ -49,6 +50,7 @@ export function PdfPreview({
   filePath,
   targetPage,
   charPositions,
+  textBbox,
   isStructuredView = false,
   activeReviewPointResultId,
   pageOffset = 0,
@@ -227,6 +229,18 @@ export function PdfPreview({
 
   // ============ 处理字符位置数据，转换为高亮矩形 ============
   const processCharPositionsToHighlights = () => {
+    // GraphRAG fallback: charPositions 为空但有 textBbox 时，用段落级坐标画高亮
+    if ((!charPositions || charPositions.length === 0) && textBbox && targetPage) {
+      const scale = zoomLevel / 100;
+      return {
+        x: textBbox.x_min * coordinateScale * scale,
+        y: textBbox.y_min * coordinateScale * scale,
+        width: (textBbox.x_max - textBbox.x_min) * coordinateScale * scale,
+        height: (textBbox.y_max - textBbox.y_min) * coordinateScale * scale,
+        text: ''
+      };
+    }
+
     if (!charPositions || charPositions.length === 0 || !targetPage) {
       return null;
     }