feat: [quote/quality] Phase 2B 견적 product_code 자동추출 + inspections work_order_id FK

- QuoteService: extractProductCodeFromInputs() 추가, store/update에서 자동 추출
- BackfillQuoteProductCodeCommand: 기존 quotes 25건 product_code 보정
- inspections 테이블에 work_order_id FK 마이그레이션 (nullable, nullOnDelete)
- Inspection↔WorkOrder 양방향 관계 추가
- InspectionService: store/show/index에 work_order_id 처리 + transformToFrontend
- InspectionStoreRequest: work_order_id 검증 규칙 추가

app/Console/Commands/BackfillQuoteProductCodeCommand.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Console\Commands;
+
+use App\Models\Quote\Quote;
+use Illuminate\Console\Command;
+
+class BackfillQuoteProductCodeCommand extends Command
+{
+    protected $signature = 'data:backfill-quote-product-code {--dry-run : 실제 저장하지 않고 결과만 출력}';
+
+    protected $description = 'quotes.product_code가 비어있는 레코드에 calculation_inputs.items[0].productCode 값 보정';
+
+    public function handle(): int
+    {
+        $dryRun = $this->option('dry-run');
+
+        $quotes = Quote::whereNull('product_code')
+            ->whereNotNull('calculation_inputs')
+            ->get();
+
+        $this->info("대상: {$quotes->count()}건".($dryRun ? ' (dry-run)' : ''));
+
+        $updated = 0;
+        $skipped = 0;
+
+        foreach ($quotes as $quote) {
+            $inputs = $quote->calculation_inputs;
+            if (! is_array($inputs)) {
+                $inputs = json_decode($inputs, true);
+            }
+
+            $productCode = $inputs['items'][0]['productCode'] ?? null;
+
+            if (! $productCode) {
+                $skipped++;
+                $this->line("  SKIP #{$quote->id} ({$quote->quote_number}) — productCode 없음");
+
+                continue;
+            }
+
+            if (! $dryRun) {
+                $quote->update(['product_code' => $productCode]);
+            }
+
+            $updated++;
+            $this->line('  '.($dryRun ? 'WOULD ' : '')."UPDATE #{$quote->id} ({$quote->quote_number}) → {$productCode}");
+        }
+
+        $this->info("완료: 보정 {$updated}건, 스킵 {$skipped}건");
+
+        return self::SUCCESS;
+    }
+}