Refactor bulk info provider: replace complex arrays with DTOs

- Add BulkSearchResponseDTO, FieldMappingDTO for type safety
- Use composition instead of inheritance in BulkSearchResultDTO
- Remove unnecessary BulkSearchRequestDTO
- Fix N+1 queries and API error handling
- Fix Add Mapping button functionality

src/Services/InfoProviderSystem/DTOs/BulkSearchResponseDTO.php

@@ -0,0 +1,122 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2023 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace App\Services\InfoProviderSystem\DTOs;
+
+/**
+ * Represents the complete response from a bulk info provider search operation.
+ * This DTO provides type safety and clear structure instead of complex arrays.
+ */
+readonly class BulkSearchResponseDTO
+{
+    /**
+     * @param PartSearchResultDTO[] $partResults Array of search results for each part
+     */
+    public function __construct(
+        public array $partResults
+    ) {}
+
+    /**
+     * Create from legacy array format for backwards compatibility.
+     * @param array $data Array of part result arrays in legacy format
+     */
+    public static function fromArray(array $data): self
+    {
+        $partResults = [];
+        foreach ($data as $partData) {
+            $partResults[] = PartSearchResultDTO::fromArray($partData);
+        }
+
+        return new self($partResults);
+    }
+
+    /**
+     * Convert to legacy array format for backwards compatibility.
+     */
+    public function toArray(): array
+    {
+        $result = [];
+        foreach ($this->partResults as $partResult) {
+            $result[] = $partResult->toArray();
+        }
+        return $result;
+    }
+
+    /**
+     * Check if any parts have search results.
+     */
+    public function hasAnyResults(): bool
+    {
+        foreach ($this->partResults as $partResult) {
+            if ($partResult->hasResults()) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Get the total number of search results across all parts.
+     */
+    public function getTotalResultCount(): int
+    {
+        $count = 0;
+        foreach ($this->partResults as $partResult) {
+            $count += $partResult->getResultCount();
+        }
+        return $count;
+    }
+
+    /**
+     * Get all parts that have search results.
+     * @return PartSearchResultDTO[]
+     */
+    public function getPartsWithResults(): array
+    {
+        return array_filter($this->partResults, fn($result) => $result->hasResults());
+    }
+
+    /**
+     * Get all parts that have errors.
+     * @return PartSearchResultDTO[]
+     */
+    public function getPartsWithErrors(): array
+    {
+        return array_filter($this->partResults, fn($result) => $result->hasErrors());
+    }
+
+    /**
+     * Get the number of parts processed.
+     */
+    public function getPartCount(): int
+    {
+        return count($this->partResults);
+    }
+
+    /**
+     * Get the number of parts with successful results.
+     */
+    public function getSuccessfulPartCount(): int
+    {
+        return count($this->getPartsWithResults());
+    }
+}