fix: decode .bin to PNG via PPM blob, not importImagePixels

The Imagick extension on the server (3.7+) requires importImagePixels
to receive an array of ints, not a string blob, so the previous code
500'd. Wrap the raw RGB bytes in a PPM (P6) header and let Imagick
decode it via readImageBlob — same result, no 70 MB-array detour.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Controller/DeviceApiController.php

@@ -243,9 +243,13 @@ class DeviceApiController extends AbstractController
             }
         }
 
+        // Wrap the raw RGB bytes in a PPM (P6) header so Imagick can decode the
+        // blob directly. importImagePixels would also work but its current
+        // signature requires an array of ints, which is ~70 MB for an 800×480.
+        $ppm = "P6\n{$width} {$height}\n255\n" . $rgb;
+
         $im = new \Imagick();
-        $im->newImage($width, $height, new \ImagickPixel('white'));
-        $im->importImagePixels(0, 0, $width, $height, 'RGB', \Imagick::PIXEL_CHAR, $rgb);
+        $im->readImageBlob($ppm);
         $im->setImageFormat('png');
         $im->writeImage($pngPath);
         $im->destroy();