feat : automatic PDF compression on upload

- Add PdfCompressorService for lossless compression with qpdf
- Add DocumentPdfCompressorListener for automatic compression on persist/update
- Add app:compress-pdf command for batch compression of existing PDFs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Service/PdfCompressorService.php

@@ -0,0 +1,73 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+class PdfCompressorService
+{
+    public function compressBase64Pdf(string $base64Data): ?array
+    {
+        // Check if qpdf is available
+        exec('which qpdf', $qpdfPath, $returnCode);
+        if (0 !== $returnCode) {
+            return null;
+        }
+
+        // Remove data URI prefix if present
+        $originalBase64 = $base64Data;
+        if (str_contains($base64Data, ',')) {
+            $base64Data = explode(',', $base64Data, 2)[1];
+        }
+
+        $pdfContent = base64_decode($base64Data, true);
+        if (false === $pdfContent) {
+            return null;
+        }
+
+        $originalSize = strlen($pdfContent);
+
+        // Create temp files
+        $tempInput  = tempnam(sys_get_temp_dir(), 'pdf_in_');
+        $tempOutput = tempnam(sys_get_temp_dir(), 'pdf_out_');
+
+        file_put_contents($tempInput, $pdfContent);
+
+        // Compress with qpdf (lossless)
+        $command = sprintf(
+            'qpdf --linearize --object-streams=generate %s %s 2>&1',
+            escapeshellarg($tempInput),
+            escapeshellarg($tempOutput)
+        );
+
+        exec($command, $cmdOutput, $returnCode);
+
+        if (0 !== $returnCode || !file_exists($tempOutput)) {
+            @unlink($tempInput);
+            @unlink($tempOutput);
+
+            return null;
+        }
+
+        $compressedContent = file_get_contents($tempOutput);
+        $compressedSize    = strlen($compressedContent);
+
+        @unlink($tempInput);
+        @unlink($tempOutput);
+
+        // Only return compressed version if it's smaller
+        if ($compressedSize >= $originalSize) {
+            return null;
+        }
+
+        // Rebuild with data URI prefix
+        $newBase64 = 'data:application/pdf;base64,'.base64_encode($compressedContent);
+
+        return [
+            'path'         => $newBase64,
+            'size'         => $compressedSize,
+            'originalSize' => $originalSize,
+            'saved'        => $originalSize - $compressedSize,
+        ];
+    }
+}