feat:고객 서비스이용 계약서 - 고객 불러오기/계약번호 자동채번/기본값

- 테넌트(고객) 검색 API 추가 (searchTenants)
- 계약번호 자동 채번 API 추가 (CONTRACT-YYYYMMDD-N 형식)
- 고객 서비스이용 계약서 선택 시 "고객 불러오기" 버튼 표시
- 고객 선택 시 상호/사업자등록번호/주소/전화번호 자동 채움
- 총개발비 기본값 20,000,000 / 월구독료 기본값 500,000 자동 세팅
- TenantSearchModal 컴포넌트 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Controllers/ESign/EsignApiController.php

@@ -13,6 +13,7 @@
 use App\Models\ESign\EsignSigner;
 use App\Models\ESign\EsignSignField;
 use App\Models\ESign\EsignAuditLog;
+use App\Models\Tenants\Tenant;
 use App\Models\Tenants\TenantSetting;
 use App\Services\Barobill\BarobillService;
 use App\Services\GoogleCloudStorageService;
@@ -73,6 +74,65 @@ public function searchPartners(Request $request): JsonResponse
         return response()->json(['success' => true, 'data' => $data]);
     }
 
+    /**
+     * 고객(테넌트) 검색
+     */
+    public function searchTenants(Request $request): JsonResponse
+    {
+        $q = trim($request->input('q', ''));
+
+        $query = Tenant::whereNull('deleted_at');
+
+        if ($q !== '') {
+            $query->where(function ($w) use ($q) {
+                $w->where('company_name', 'like', "%{$q}%")
+                  ->orWhere('business_num', 'like', "%{$q}%")
+                  ->orWhere('phone', 'like', "%{$q}%")
+                  ->orWhere('ceo_name', 'like', "%{$q}%");
+            });
+        }
+
+        $tenants = $query->orderBy('company_name')->limit(20)->get();
+
+        $data = $tenants->map(fn($t) => [
+            'id' => $t->id,
+            'company_name' => $t->company_name,
+            'business_num' => $t->business_num,
+            'ceo_name' => $t->ceo_name,
+            'address' => $t->address,
+            'phone' => $t->phone,
+            'email' => $t->email,
+        ]);
+
+        return response()->json(['success' => true, 'data' => $data]);
+    }
+
+    /**
+     * 계약번호 자동 채번 (CONTRACT-YYYY-MMDD-N)
+     */
+    public function generateContractNumber(): JsonResponse
+    {
+        $tenantId = session('selected_tenant_id', 1);
+        $today = now()->format('Ymd');
+        $prefix = "CONTRACT-{$today}-";
+
+        $lastContract = EsignContract::where('tenant_id', $tenantId)
+            ->where('contract_code', 'like', "{$prefix}%")
+            ->orderByRaw("CAST(SUBSTRING(contract_code, ?) AS UNSIGNED) DESC", [strlen($prefix) + 1])
+            ->first();
+
+        $seq = 1;
+        if ($lastContract) {
+            $lastSeq = (int) str_replace($prefix, '', $lastContract->contract_code);
+            $seq = $lastSeq + 1;
+        }
+
+        return response()->json([
+            'success' => true,
+            'data' => ['contract_number' => $prefix . $seq],
+        ]);
+    }
+
     /**
      * 법인도장 조회
      */