feat: add unique constraint for immich_id per user in AdventureImage model and enhance Immich integration image retrieval

backend/server/adventures/migrations/0033_adventureimage_unique_immich_id_per_user.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.2.1 on 2025-06-02 02:31
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('adventures', '0032_remove_adventureimage_image_xor_immich_id'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name='adventureimage',
+            constraint=models.UniqueConstraint(fields=('immich_id', 'user_id'), name='unique_immich_id_per_user'),
+        ),
+    ]

backend/server/adventures/migrations/0034_remove_adventureimage_unique_immich_id_per_user.py

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+# Generated by Django 5.2.1 on 2025-06-02 02:44
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('adventures', '0033_adventureimage_unique_immich_id_per_user'),
+    ]
+
+    operations = [
+        migrations.RemoveConstraint(
+            model_name='adventureimage',
+            name='unique_immich_id_per_user',
+        ),
+    ]