fix restore choice options in local PDF rendering

Backfill choice options from question bank when paper question rows do not carry options, so local Blade rendering shows A/B/C/D choices correctly.

Made-with: Cursor

app/Services/ExamPdfExportService.php

@@ -2010,9 +2010,39 @@ class ExamPdfExportService
 
             // 构造视图需要的变量
             $questions = ['choice' => [], 'fill' => [], 'answer' => []];
+            $questionBankIds = $paper->questions
+                ->pluck('question_bank_id')
+                ->filter()
+                ->unique()
+                ->values();
+            $optionsByBankId = [];
+            if ($questionBankIds->isNotEmpty()) {
+                $optionsByBankId = Question::whereIn('id', $questionBankIds)
+                    ->pluck('options', 'id')
+                    ->toArray();
+            }
             foreach ($paper->questions as $pq) {
                 $qType = $this->normalizeQuestionType($pq->question_type ?? 'answer');
-                $questions[$qType][] = $this->normalizeAnswerFieldForPdf($pq);
+                $normalizedQuestion = $this->normalizeAnswerFieldForPdf($pq);
+
+                // 本地渲染链路下，paper_questions 通常不带 options，需要从题库回填选择题选项。
+                if ($qType === 'choice') {
+                    $options = $normalizedQuestion->options ?? null;
+                    if (empty($options) && ! empty($normalizedQuestion->question_bank_id)) {
+                        $options = $optionsByBankId[$normalizedQuestion->question_bank_id] ?? null;
+                    }
+                    if (is_string($options)) {
+                        $decoded = json_decode($options, true);
+                        if (json_last_error() === JSON_ERROR_NONE) {
+                            $options = $decoded;
+                        }
+                    }
+                    if (is_array($options)) {
+                        $normalizedQuestion->options = $options;
+                    }
+                }
+
+                $questions[$qType][] = $normalizedQuestion;
             }
 
             $studentModel = \App\Models\Student::find($paper->student_id);