fix: include orientation in device 304 cache check

The 304 short-circuit at DeviceImageController only compared image IDs,
so flipping a device between landscape and portrait would not invalidate
the cache: the device kept showing the previously-rendered .bin even
after the user changed orientation in the webapp.

Now the device row tracks currentImageOrientation — set whenever a 200
binary response is sent — and the 304 path requires both image id AND
current orientation to match the device's stored orientation. An
orientation flip naturally falls through to the 200 path on the next
poll, the freshly-rendered portrait .bin is delivered, and the device
redraws.

No firmware change: the existing X-Current-Image-Id header from the
device is sufficient. Existing devices migrate cleanly — null
currentImageOrientation just forces one full re-send on first post-
migration poll, which is harmless.

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

migrations/Version20260507210000.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+final class Version20260507210000 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Add device.current_image_orientation so 304 cache check can detect orientation flips';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE device ADD current_image_orientation VARCHAR(255) DEFAULT NULL');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE device DROP COLUMN current_image_orientation');
+    }
+}