feat(documents) : filesystem storage, server-side pagination and PDF compression

- Add DocumentStorageService for file-based storage (replaces Base64 in DB)
- Add DocumentServeController with /file and /download endpoints
- Add DocumentUploadProcessor using FormData + filesystem storage
- Add DocumentNormalizer exposing fileUrl/downloadUrl on all responses
- Add DocumentFileCleanupListener for automatic file deletion
- Add MigrateDocumentsToFilesystemCommand (Base64 → files, memory-safe)
- Add ApiFilter (SearchFilter, ExistsFilter, OrderFilter) on Document entity
- Add PdfCompressorService + refactor CompressPdfCommand for batch processing
- Fix TypeMachine PUT: deserialize=false + validate=false to prevent
  UniqueEntity false positive and writableLink collection interference
- Update CHANGELOG for v1.8.0
- Update frontend submodule

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

src/Service/PdfCompressorService.php

@@ -6,6 +6,63 @@ namespace App\Service;
 
 class PdfCompressorService
 {
+    /**
+     * Compress an actual PDF file on disk. Returns metadata or null if no gain.
+     *
+     * @return null|array{size: int, originalSize: int, saved: int}
+     */
+    public function compressFile(string $absolutePath): ?array
+    {
+        exec('which qpdf', $qpdfPath, $returnCode);
+        if (0 !== $returnCode) {
+            return null;
+        }
+
+        if (!file_exists($absolutePath)) {
+            return null;
+        }
+
+        $originalSize = filesize($absolutePath);
+        if (false === $originalSize) {
+            return null;
+        }
+
+        $tempOutput = tempnam(sys_get_temp_dir(), 'pdf_out_');
+
+        $command = sprintf(
+            'qpdf --linearize --object-streams=generate %s %s 2>&1',
+            escapeshellarg($absolutePath),
+            escapeshellarg($tempOutput)
+        );
+
+        exec($command, $cmdOutput, $returnCode);
+
+        if (0 !== $returnCode || !file_exists($tempOutput)) {
+            @unlink($tempOutput);
+
+            return null;
+        }
+
+        $compressedSize = filesize($tempOutput);
+        if (false === $compressedSize || $compressedSize >= $originalSize) {
+            @unlink($tempOutput);
+
+            return null;
+        }
+
+        if (!rename($tempOutput, $absolutePath)) {
+            @unlink($tempOutput);
+
+            return null;
+        }
+
+        return [
+            'size'         => $compressedSize,
+            'originalSize' => $originalSize,
+            'saved'        => $originalSize - $compressedSize,
+        ];
+    }
+
     public function compressBase64Pdf(string $base64Data): ?array
     {
         // Check if qpdf is available